• Grounded grid VHF front-end

    From Liz Tuddenham@21:1/5 to All on Sat Nov 9 16:35:45 2024
    My current receiving aerial system is very inefficient at 2 metres (144
    Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a
    small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old
    Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television
    sets working at about 45 Mc/s, so it can't have too bad a noise figure (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce
    the noise and increase the maximum frequency it could usefully amplify.
    From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the
    cathode of 160 ohms. A 75-ohm feeder could be matched to this with a
    Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad
    thing because it would allow extra tuned circuits to give better image rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to Liz Tuddenham on Sat Nov 9 08:59:29 2024
    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144
    Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a
    small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old
    Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television
    sets working at about 45 Mc/s, so it can't have too bad a noise figure >(although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce
    the noise and increase the maximum frequency it could usefully amplify.
    From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the
    cathode of 160 ohms. A 75-ohm feeder could be matched to this with a
    Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad
    thing because it would allow extra tuned circuits to give better image >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric
    noise still dominates.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to Liz Tuddenham on Sat Nov 9 20:02:05 2024
    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144
    Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a
    small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old
    Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television
    sets working at about 45 Mc/s, so it can't have too bad a noise figure
    (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce
    the noise and increase the maximum frequency it could usefully amplify.
    From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the
    cathode of 160 ohms. A 75-ohm feeder could be matched to this with a
    Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded
    cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad
    thing because it would allow extra tuned circuits to give better image
    rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric
    noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on
    the downlead. If the down-converter is adjacent to the HF receiver,
    there will be significant losses at VHF in the downlead, as the aerial
    needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >signal could be radiated by the aerial - especially if it happens to lie
    at a frequency where the dipole has another resonance or the dipole and >downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial
    (the sleeve dipole has a 'cold' bottom end and could be joined directly
    onto the converter box). The HT and LT could be supplied either by a >separate multi-core cable or by superimposing 40v A.C. at 50c/s on the
    co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an >auto-transformer to give 250v H.T. and the secondary could give 6.3v or
    12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL
    handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to john larkin on Sat Nov 9 19:27:13 2024
    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >Mc/s) and I have thought about making a sleeve dipole for that band. My >VHF receiver is an Eddystone 770R, which covers the band but only in a >small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television
    sets working at about 45 Mc/s, so it can't have too bad a noise figure >(although Mullard don't quote one in their data sheet). If I >triode-strapped it and ran it in grounded grid mode, that would reduce
    the noise and increase the maximum frequency it could usefully amplify. >From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the >cathode of 160 ohms. A 75-ohm feeder could be matched to this with a
    Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct >neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad >thing because it would allow extra tuned circuits to give better image >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric
    noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on
    the downlead. If the down-converter is adjacent to the HF receiver,
    there will be significant losses at VHF in the downlead, as the aerial
    needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator
    signal could be radiated by the aerial - especially if it happens to lie
    at a frequency where the dipole has another resonance or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial
    (the sleeve dipole has a 'cold' bottom end and could be joined directly
    onto the converter box). The HT and LT could be supplied either by a
    separate multi-core cable or by superimposing 40v A.C. at 50c/s on the
    co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v or
    12.6v to run the heaters.

    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Cursitor Doom on Sat Nov 9 20:26:18 2024
    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >> >Mc/s) and I have thought about making a sleeve dipole for that band. My >> >VHF receiver is an Eddystone 770R, which covers the band but only in a
    small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges >> >of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but >> >not necessarily the expensive 'cult' ones which everyone seems to regard >> >as having magical powers. The EF91 is plentiful and cheap as New Old
    Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television
    sets working at about 45 Mc/s, so it can't have too bad a noise figure
    (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce
    the noise and increase the maximum frequency it could usefully amplify. >> >From the data sheet, with 200v on anode and grid 2 and an anode current >> >of 6mA, the gm is about 6mA/V, which gives an input impedance at the
    cathode of 160 ohms. A 75-ohm feeder could be matched to this with a
    Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >> >cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as >> >a mixer, I might need one more stage of RF gain to get the signal up to >> >a level where the mixer noise is negligible - but this isn't such a bad >> >thing because it would allow extra tuned circuits to give better image
    rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric
    noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on >the downlead. If the down-converter is adjacent to the HF receiver,
    there will be significant losses at VHF in the downlead, as the aerial >needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >signal could be radiated by the aerial - especially if it happens to lie
    at a frequency where the dipole has another resonance or the dipole and >downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >(the sleeve dipole has a 'cold' bottom end and could be joined directly >onto the converter box). The HT and LT could be supplied either by a >separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an >auto-transformer to give 250v H.T. and the secondary could give 6.3v or >12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I have read most of that sort of literature in the past and still have
    copies of most of it but don't remember this particular approach being
    used before - that was why I though it might make a good fun project.
    There are some grounded-grid circuits but they use triodes intended for
    the purpose. There are cascode circuits with double (and sometimes two
    single) triodes but, again, the triodes are intended for that purpose.
    The idea of using a bog-standard descendent of the ubiquitous EF50 for frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the wideband front end of a noise-measuring set that I designed; it gave
    very satisfactory results.


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to All on Sat Nov 9 12:21:41 2024
    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >>> >Mc/s) and I have thought about making a sleeve dipole for that band. My >>> >VHF receiver is an Eddystone 770R, which covers the band but only in a
    small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges >>> >of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but >>> >not necessarily the expensive 'cult' ones which everyone seems to regard >>> >as having magical powers. The EF91 is plentiful and cheap as New Old
    Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television
    sets working at about 45 Mc/s, so it can't have too bad a noise figure
    (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce
    the noise and increase the maximum frequency it could usefully amplify. >>> >From the data sheet, with 200v on anode and grid 2 and an anode current >>> >of 6mA, the gm is about 6mA/V, which gives an input impedance at the
    cathode of 160 ohms. A 75-ohm feeder could be matched to this with a
    Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >>> >cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as >>> >a mixer, I might need one more stage of RF gain to get the signal up to >>> >a level where the mixer noise is negligible - but this isn't such a bad >>> >thing because it would allow extra tuned circuits to give better image
    rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric
    noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on >>the downlead. If the down-converter is adjacent to the HF receiver,
    there will be significant losses at VHF in the downlead, as the aerial >>needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>signal could be radiated by the aerial - especially if it happens to lie
    at a frequency where the dipole has another resonance or the dipole and >>downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>(the sleeve dipole has a 'cold' bottom end and could be joined directly >>onto the converter box). The HT and LT could be supplied either by a >>separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an >>auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL >handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to john larkin on Sat Nov 9 21:03:12 2024
    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >>>> >Mc/s) and I have thought about making a sleeve dipole for that band. My >>>> >VHF receiver is an Eddystone 770R, which covers the band but only in a >>>> >small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges >>>> >of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>> >scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but >>>> >not necessarily the expensive 'cult' ones which everyone seems to regard >>>> >as having magical powers. The EF91 is plentiful and cheap as New Old >>>> >Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television >>>> >sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>> >(although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>> >the noise and increase the maximum frequency it could usefully amplify. >>>> >From the data sheet, with 200v on anode and grid 2 and an anode current >>>> >of 6mA, the gm is about 6mA/V, which gives an input impedance at the
    cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>> >Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >>>> >cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as >>>> >a mixer, I might need one more stage of RF gain to get the signal up to >>>> >a level where the mixer noise is negligible - but this isn't such a bad >>>> >thing because it would allow extra tuned circuits to give better image >>>> >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on >>>the downlead. If the down-converter is adjacent to the HF receiver, >>>there will be significant losses at VHF in the downlead, as the aerial >>>needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>signal could be radiated by the aerial - especially if it happens to lie >>>at a frequency where the dipole has another resonance or the dipole and >>>downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>(the sleeve dipole has a 'cold' bottom end and could be joined directly >>>onto the converter box). The HT and LT could be supplied either by a >>>separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>co-ax and feeding it into the 200-220-240v tappings.of a mains >>>transformer primary. The full primary winding would act as an >>>auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL >>handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group
    today who can really add any value here. Ham group, Liz; ham group.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Cursitor Doom on Sat Nov 9 21:40:06 2024
    Cursitor Doom <cd@notformail.com> wrote:

    [...]
    There's not a single person on this group
    today who can really add any value here.

    You do them a dis-service, there are some people here who can think with
    an open mind. Even if the ideas they come up with wouldn't work, trying
    to find out or explain why they wouldn't work is a good exercise and may
    lead to a better solution than just asking hams what they have done
    before.


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Joe Gwinn@21:1/5 to All on Sat Nov 9 16:48:10 2024
    On Sat, 09 Nov 2024 21:03:12 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com> >>wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >>>>> >Mc/s) and I have thought about making a sleeve dipole for that band. My >>>>> >VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>> >small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that >>>>> >would allow me to use an HF communications receiver or the lower ranges >>>>> >of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>> >scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but >>>>> >not necessarily the expensive 'cult' ones which everyone seems to regard >>>>> >as having magical powers. The EF91 is plentiful and cheap as New Old >>>>> >Stock, so that seems like a good valve to start playing about with. >>>>> >
    The EF91 was used as an RF amplifier in the input stages of television >>>>> >sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>>> >(although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>>> >the noise and increase the maximum frequency it could usefully amplify. >>>>> >From the data sheet, with 200v on anode and grid 2 and an anode current >>>>> >of 6mA, the gm is about 6mA/V, which gives an input impedance at the >>>>> >cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>>> >Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >>>>> >cathode mode, but it allows the valve to be triode strapped for low >>>>> >noise without instability problems or the dependence on neutralising >>>>> >that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as >>>>> >a mixer, I might need one more stage of RF gain to get the signal up to >>>>> >a level where the mixer noise is negligible - but this isn't such a bad >>>>> >thing because it would allow extra tuned circuits to give better image >>>>> >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF >>>>receiver is almost certain to suffer from strong HF signals picked up on >>>>the downlead. If the down-converter is adjacent to the HF receiver, >>>>there will be significant losses at VHF in the downlead, as the aerial >>>>needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>>signal could be radiated by the aerial - especially if it happens to lie >>>>at a frequency where the dipole has another resonance or the dipole and >>>>downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>>(the sleeve dipole has a 'cold' bottom end and could be joined directly >>>>onto the converter box). The HT and LT could be supplied either by a >>>>separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>>co-ax and feeding it into the 200-220-240v tappings.of a mains >>>>transformer primary. The full primary winding would act as an >>>>auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>>12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour. >>>However, there should be tons of info on this in one of the old ARRL >>>handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group
    today who can really add any value here. Ham group, Liz; ham group.

    I know a lot of receiver designers, and the older ones are all Hams.

    Joe

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Cursitor Doom on Sat Nov 9 22:52:16 2024
    Cursitor Doom <cd@notformail.com> wrote:
    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >>>>>> Mc/s) and I have thought about making a sleeve dipole for that band. My >>>>>> VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>>> small portion of the whole scale. While I am improvomg the aerial >>>>>> system, I could also make a crystal-controlled down-converter, that >>>>>> would allow me to use an HF communications receiver or the lower ranges >>>>>> of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>>> scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but >>>>>> not necessarily the expensive 'cult' ones which everyone seems to regard >>>>>> as having magical powers. The EF91 is plentiful and cheap as New Old >>>>>> Stock, so that seems like a good valve to start playing about with. >>>>>>
    The EF91 was used as an RF amplifier in the input stages of television >>>>>> sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>>>> (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>>>> the noise and increase the maximum frequency it could usefully amplify. >>>>>> From the data sheet, with 200v on anode and grid 2 and an anode current >>>>>> of 6mA, the gm is about 6mA/V, which gives an input impedance at the >>>>>> cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>>>> Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >>>>>> cathode mode, but it allows the valve to be triode strapped for low >>>>>> noise without instability problems or the dependence on neutralising >>>>>> that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as >>>>>> a mixer, I might need one more stage of RF gain to get the signal up to >>>>>> a level where the mixer noise is negligible - but this isn't such a bad >>>>>> thing because it would allow extra tuned circuits to give better image >>>>>> rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on >>>> the downlead. If the down-converter is adjacent to the HF receiver,
    there will be significant losses at VHF in the downlead, as the aerial >>>> needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>> signal could be radiated by the aerial - especially if it happens to lie >>>> at a frequency where the dipole has another resonance or the dipole and >>>> downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>> (the sleeve dipole has a 'cold' bottom end and could be joined directly >>>> onto the converter box). The HT and LT could be supplied either by a
    separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>> co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>> 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL
    handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group
    today who can really add any value here. Ham group, Liz; ham group.


    2 metres is pretty much DC nowadays anyhow.

    HF receivers don’t have to have good noise performance because the
    atmosphere is so noisy, and AFAICT they usually don’t. Intermod is more of an issue.

    The atmosphere is quieter above 100 MHz, though, so you care more about the
    Rx noise figure.

    A mixer front end is going to have a noise figure of 6 dB or so, on account
    of the conversion loss, and that adds to the NF of the HF back end.

    Some gain ahead of the mixer, and some more following the band select
    filter should help a lot. Don’t overdo it, of course.

    Cheers

    Phil Hobbs


    --
    D r Philip C D Hobbs Principal Consultant Electro Optical Innovations
    LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to Liz Tuddenham on Sat Nov 9 15:39:29 2024
    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >> >> >Mc/s) and I have thought about making a sleeve dipole for that band. My >> >> >VHF receiver is an Eddystone 770R, which covers the band but only in a >> >> >small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges >> >> >of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but >> >> >not necessarily the expensive 'cult' ones which everyone seems to regard >> >> >as having magical powers. The EF91 is plentiful and cheap as New Old
    Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television >> >> >sets working at about 45 Mc/s, so it can't have too bad a noise figure >> >> >(although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >> >> >the noise and increase the maximum frequency it could usefully amplify. >> >> >From the data sheet, with 200v on anode and grid 2 and an anode current >> >> >of 6mA, the gm is about 6mA/V, which gives an input impedance at the
    cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >> >> >Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >> >> >cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as >> >> >a mixer, I might need one more stage of RF gain to get the signal up to >> >> >a level where the mixer noise is negligible - but this isn't such a bad >> >> >thing because it would allow extra tuned circuits to give better image >> >> >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric
    noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on
    the downlead. If the down-converter is adjacent to the HF receiver,
    there will be significant losses at VHF in the downlead, as the aerial
    needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator
    signal could be radiated by the aerial - especially if it happens to lie
    at a frequency where the dipole has another resonance or the dipole and
    downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial
    (the sleeve dipole has a 'cold' bottom end and could be joined directly
    onto the converter box). The HT and LT could be supplied either by a
    separate multi-core cable or by superimposing 40v A.C. at 50c/s on the
    co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v or
    12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL
    handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I have read most of that sort of literature in the past and still have
    copies of most of it but don't remember this particular approach being
    used before - that was why I though it might make a good fun project.
    There are some grounded-grid circuits but they use triodes intended for
    the purpose. There are cascode circuits with double (and sometimes two >single) triodes but, again, the triodes are intended for that purpose.
    The idea of using a bog-standard descendent of the ubiquitous EF50 for >frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a >triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the >wideband front end of a noise-measuring set that I designed; it gave
    very satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact -
    comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low
    value resistor, a Q killer.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Dan Green@21:1/5 to All on Sat Nov 9 23:23:59 2024
    On Sat, 09 Nov 2024 16:48:10 -0500, Joe Gwinn <joegwinn@comcast.net>
    wrote:

    On Sat, 09 Nov 2024 21:03:12 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com> >>>wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid >>>>(Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >>>>>> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >>>>>> >Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>>> >small portion of the whole scale. While I am improvomg the aerial >>>>>> >system, I could also make a crystal-controlled down-converter, that >>>>>> >would allow me to use an HF communications receiver or the lower ranges >>>>>> >of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>>> >scale length.

    It's been a few years since I designed anything with valves, so I >>>>>> >thought I might have a go at making a down-converter using valves - but >>>>>> >not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >>>>>> >Stock, so that seems like a good valve to start playing about with. >>>>>> >
    The EF91 was used as an RF amplifier in the input stages of television >>>>>> >sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>>>> >(although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>>>> >the noise and increase the maximum frequency it could usefully amplify. >>>>>> >From the data sheet, with 200v on anode and grid 2 and an anode current >>>>>> >of 6mA, the gm is about 6mA/V, which gives an input impedance at the >>>>>> >cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>>>> >Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded
    cathode mode, but it allows the valve to be triode strapped for low >>>>>> >noise without instability problems or the dependence on neutralising >>>>>> >that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to >>>>>> >a level where the mixer noise is negligible - but this isn't such a bad >>>>>> >thing because it would allow extra tuned circuits to give better image >>>>>> >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF >>>>>receiver is almost certain to suffer from strong HF signals picked up on >>>>>the downlead. If the down-converter is adjacent to the HF receiver, >>>>>there will be significant losses at VHF in the downlead, as the aerial >>>>>needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>>>signal could be radiated by the aerial - especially if it happens to lie >>>>>at a frequency where the dipole has another resonance or the dipole and >>>>>downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>>>(the sleeve dipole has a 'cold' bottom end and could be joined directly >>>>>onto the converter box). The HT and LT could be supplied either by a >>>>>separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>>>co-ax and feeding it into the 200-220-240v tappings.of a mains >>>>>transformer primary. The full primary winding would act as an >>>>>auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>>>12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour. >>>>However, there should be tons of info on this in one of the old ARRL >>>>handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group >>today who can really add any value here. Ham group, Liz; ham group.

    I know a lot of receiver designers, and the older ones are all Hams.

    Joe

    +1
    That's where all the expertise is. Esp. with tubes.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to All on Sat Nov 9 15:41:09 2024
    On Sat, 09 Nov 2024 23:23:59 +0000, Dan Green <dhg99908@hotmail.se>
    wrote:

    On Sat, 09 Nov 2024 16:48:10 -0500, Joe Gwinn <joegwinn@comcast.net>
    wrote:

    On Sat, 09 Nov 2024 21:03:12 +0000, Cursitor Doom <cd@notformail.com> >>wrote:

    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com> >>>>wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid >>>>>(Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >>>>>>> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144
    Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>>>> >small portion of the whole scale. While I am improvomg the aerial >>>>>>> >system, I could also make a crystal-controlled down-converter, that >>>>>>> >would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>>>> >scale length.

    It's been a few years since I designed anything with valves, so I >>>>>>> >thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >>>>>>> >Stock, so that seems like a good valve to start playing about with. >>>>>>> >
    The EF91 was used as an RF amplifier in the input stages of television >>>>>>> >sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>>>>> >(although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>>>>> >the noise and increase the maximum frequency it could usefully amplify.
    From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the >>>>>>> >cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>>>>> >Pi tank or by tapping the L or the C of an input tumed circuit. >>>>>>> >
    The voltage gain may not be as high in this configuration as in grounded
    cathode mode, but it allows the valve to be triode strapped for low >>>>>>> >noise without instability problems or the dependence on neutralising >>>>>>> >that a cascode stage would have (especially the need for correct >>>>>>> >neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad
    thing because it would allow extra tuned circuits to give better image >>>>>>> >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves? >>>>>>>

    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>>>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF >>>>>>receiver is almost certain to suffer from strong HF signals picked up on >>>>>>the downlead. If the down-converter is adjacent to the HF receiver, >>>>>>there will be significant losses at VHF in the downlead, as the aerial >>>>>>needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>>>>signal could be radiated by the aerial - especially if it happens to lie >>>>>>at a frequency where the dipole has another resonance or the dipole and >>>>>>downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>>>>(the sleeve dipole has a 'cold' bottom end and could be joined directly >>>>>>onto the converter box). The HT and LT could be supplied either by a >>>>>>separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>>>>co-ax and feeding it into the 200-220-240v tappings.of a mains >>>>>>transformer primary. The full primary winding would act as an >>>>>>auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>>>>12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due >>>>>respect - will be able to assist you very much in this endeavour. >>>>>However, there should be tons of info on this in one of the old ARRL >>>>>handbooks. If you have any from the early 60s lying around it should >>>>>be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and >>>trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people >>>here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group >>>today who can really add any value here. Ham group, Liz; ham group.

    I know a lot of receiver designers, and the older ones are all Hams.

    Joe

    +1
    That's where all the expertise is. Esp. with tubes.

    Tubes are noisy. There are MMICS with NFs below 1 dB.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Chris Jones@21:1/5 to Phil Hobbs on Sun Nov 10 11:35:07 2024
    On 10/11/2024 9:52 am, Phil Hobbs wrote:
    Cursitor Doom <cd@notformail.com> wrote:
    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >>>>>> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >>>>>>> Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>>>> small portion of the whole scale. While I am improvomg the aerial >>>>>>> system, I could also make a crystal-controlled down-converter, that >>>>>>> would allow me to use an HF communications receiver or the lower ranges >>>>>>> of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>>>> scale length.

    It's been a few years since I designed anything with valves, so I >>>>>>> thought I might have a go at making a down-converter using valves - but >>>>>>> not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >>>>>>> Stock, so that seems like a good valve to start playing about with. >>>>>>>
    The EF91 was used as an RF amplifier in the input stages of television >>>>>>> sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>>>>> (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>>>>> the noise and increase the maximum frequency it could usefully amplify. >>>>>>> From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the >>>>>>> cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>>>>> Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded
    cathode mode, but it allows the valve to be triode strapped for low >>>>>>> noise without instability problems or the dependence on neutralising >>>>>>> that a cascode stage would have (especially the need for correct >>>>>>> neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to >>>>>>> a level where the mixer noise is negligible - but this isn't such a bad >>>>>>> thing because it would allow extra tuned circuits to give better image >>>>>>> rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on >>>>> the downlead. If the down-converter is adjacent to the HF receiver, >>>>> there will be significant losses at VHF in the downlead, as the aerial >>>>> needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>>> signal could be radiated by the aerial - especially if it happens to lie >>>>> at a frequency where the dipole has another resonance or the dipole and >>>>> downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>>> (the sleeve dipole has a 'cold' bottom end and could be joined directly >>>>> onto the converter box). The HT and LT could be supplied either by a >>>>> separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>>> co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>>> 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL
    handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group
    today who can really add any value here. Ham group, Liz; ham group.


    2 metres is pretty much DC nowadays anyhow.

    HF receivers don’t have to have good noise performance because the atmosphere is so noisy, and AFAICT they usually don’t. Intermod is more of an issue.

    The atmosphere is quieter above 100 MHz, though, so you care more about the Rx noise figure.

    A mixer front end is going to have a noise figure of 6 dB or so, on account of the conversion loss, and that adds to the NF of the HF back end.

    Some gain ahead of the mixer, and some more following the band select
    filter should help a lot. Don’t overdo it, of course.

    Cheers

    Phil Hobbs



    All correct.

    On 2m, a decent noise figure is worth achieving. It seems to me that at
    144MHz, using valves/tubes is going to make the whole design much
    harder. (If nothing else, due to the wiring inductance and capacitance
    of sockets.) Of course there are coaxial valves working up to microwave frequencies, but the selection available now is going to be much more
    sparse than in the 1960s, so designing with the valves available now is
    going to he harder than designing with valves back then, and much harder
    than designing with ICs now.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Liz Tuddenham on Sun Nov 10 06:08:27 2024
    On a sunny day (Sat, 9 Nov 2024 16:35:45 +0000) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1r2rj8l.msi28f14weovyN%liz@poppyrecords.invalid.invalid>:

    My current receiving aerial system is very inefficient at 2 metres (144
    Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a
    small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    Have you ever considered using a RTL_SDR stick and a PC or Raspberry program for reception?
    Something I wrote for it:
    https://panteltje.nl/pub/xpsa-0.7.gif
    those sticks cover from about 20 MHz to 1.6 GHz
    More abou those here:
    https://www.rtl-sdr.com/about-rtl-sdr/
    even used one to receive GPS signals
    Those sticks are about 40? dollars on ebay, accuracy 1 ppm.
    https://www.ebay.com/itm/276000566513?



    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old
    Stock, so that seems like a good valve to start playing about with.

    I remember ECC85 in FM tuners, should be fine at 144 MHz:
    https://www.radiomuseum.org/tubes/tube_ecc85.html

    That circuit diagram shows an about 100 MHz to 10.7 MHz FM radio input stage + mixer.
    I have used that tube a few times.

    But transistors took over, and now chips like in that RTL_SDR stick, are hard to beat.

    Sometimes I just strip some coax at the right length for antenna:
    https://www.panteltje.nl/pub/DVB-T2_antenna_IXIMG_0757.JPG
    Have some yagi antennas too, and even an old TV rack..
    And a big 27 MHz GPA antenna somewhere...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Liz Tuddenham on Sun Nov 10 06:15:09 2024
    On a sunny day (Sat, 9 Nov 2024 21:40:06 +0000) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1r2ryhd.13zcmw333xq46N%liz@poppyrecords.invalid.invalid>:

    Cursitor Doom <cd@notformail.com> wrote:

    [...]
    There's not a single person on this group
    today who can really add any value here.

    You do them a dis-service, there are some people here who can think with
    an open mind. Even if the ideas they come up with wouldn't work, trying
    to find out or explain why they wouldn't work is a good exercise and may
    lead to a better solution than just asking hams what they have done
    before.

    Dual gate MOSFETs were fun too:-)
    Used a lot of that.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to All on Sun Nov 10 06:28:06 2024
    PS
    I have a PSARK 100 antenna analyzer
    https://panteltje.nl/pub/SARK100_on_dummy_antenna_IMG_4508.JPG
    and played with inductive loop antennas:
    https://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_IMG_4536.JPG
    https://panteltje.nl/pub/testing_the_20_meter_inductive_loop_antenna_dunno_IMG_4537.JPG
    wrote some software for it:
    https://panteltje.nl/panteltje/newsflex/download.html#psark100
    Just experiments, learning curve..
    toobes?

    Still have a CRT color monitor upstairs (not in use)..
    my personal particle accelerator!!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to john larkin on Sun Nov 10 08:00:17 2024
    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres
    (144 Mc/s) and I have thought about making a sleeve dipole for that
    band. My VHF receiver is an Eddystone 770R, which covers the band
    but only in a small portion of the whole scale. While I am
    improvomg the aerial system, I could also make a crystal-controlled
    down-converter, that would allow me to use an HF communications
    receiver or the lower ranges of the 770R, so that the band 2 Mc/s
    wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves -
    but not necessarily the expensive 'cult' ones which everyone seems
    to regard as having magical powers. The EF91 is plentiful and
    cheap as New Old Stock, so that seems like a good valve to start
    playing about with.

    The EF91 was used as an RF amplifier in the input stages of
    television sets working at about 45 Mc/s, so it can't have too bad
    a noise figure (although Mullard don't quote one in their data
    sheet). If I triode-strapped it and ran it in grounded grid mode,
    that would reduce the noise and increase the maximum frequency it
    could usefully amplify. From the data sheet, with 200v on anode and
    grid 2 and an anode current of 6mA, the gm is about 6mA/V, which
    gives an input impedance at the cathode of 160 ohms. A 75-ohm
    feeder could be matched to this with a Pi tank or by tapping the L
    or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in
    grounded cathode mode, but it allows the valve to be triode
    strapped for low noise without instability problems or the
    dependence on neutralising that a cascode stage would have
    (especially the need for correct neutralising to obtain the best
    noise figure). If I also use an EF91 as a mixer, I might need one
    more stage of RF gain to get the signal up to a level where the
    mixer noise is negligible - but this isn't such a bad thing because
    it would allow extra tuned circuits to give better image rejection
    and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up
    on the downlead. If the down-converter is adjacent to the HF
    receiver, there will be significant losses at VHF in the downlead, as
    the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local
    oscillator signal could be radiated by the aerial - especially if it
    happens to lie at a frequency where the dipole has another resonance
    or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the
    aerial (the sleeve dipole has a 'cold' bottom end and could be joined
    directly onto the converter box). The HT and LT could be supplied
    either by a separate multi-core cable or by superimposing 40v A.C. at
    50c/s on the co-ax and feeding it into the 200-220-240v tappings.of a
    mains transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v
    or 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due respect
    - will be able to assist you very much in this endeavour. However,
    there should be tons of info on this in one of the old ARRL handbooks.
    If you have any from the early 60s lying around it should be well worth
    a look through.

    I have read most of that sort of literature in the past and still have >copies of most of it but don't remember this particular approach being
    used before - that was why I though it might make a good fun project.
    There are some grounded-grid circuits but they use triodes intended for
    the purpose. There are cascode circuits with double (and sometimes two >single) triodes but, again, the triodes are intended for that purpose.
    The idea of using a bog-standard descendent of the ubiquitous EF50 for >frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a >triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the >wideband front end of a noise-measuring set that I designed; it gave very >satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact -
    comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low
    value resistor, a Q killer.

    Series-tuned input circuit.

    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to All on Sun Nov 10 08:00:16 2024
    john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 16:48:10 -0500, Joe Gwinn <joegwinn@comcast.net>
    wrote:

    On Sat, 09 Nov 2024 23:23:59 +0000, Dan Green <dhg99908@hotmail.se>
    wrote:
    [...]
    I know a lot of receiver designers, and the older ones are all Hams.

    Joe

    +1
    That's where all the expertise is. Esp. with tubes.

    Unfortunately there are a lot of people working with valves who aren't engineers and simply cobble together circuits based on myths, legends
    and 'golden ears'. The voices of the real engineers who understand
    valves are lost in a din of technobabble.


    Tubes are noisy. There are MMICS with NFs below 1 dB.

    There are quiet valves (Nuvistors) and noisy transistors (many),
    engineering is a matter of chosing the right ones or using them in a way
    which minimises the noise or makes it less significant in the overall
    design.

    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to Phil Hobbs on Sun Nov 10 08:00:17 2024
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Cursitor Doom <cd@notformail.com> wrote:
    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >>>>> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres >>>>>> (144 Mc/s) and I have thought about making a sleeve dipole for that >>>>>> band. My VHF receiver is an Eddystone 770R, which covers the band >>>>>> but only in a small portion of the whole scale. While I am
    improvomg the aerial system, I could also make a crystal-controlled >>>>>> down-converter, that would allow me to use an HF communications
    receiver or the lower ranges of the 770R, so that the band 2 Mc/s >>>>>> wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I >>>>>> thought I might have a go at making a down-converter using valves - >>>>>> but not necessarily the expensive 'cult' ones which everyone seems >>>>>> to regard as having magical powers. The EF91 is plentiful and
    cheap as New Old Stock, so that seems like a good valve to start >>>>>> playing about with.

    The EF91 was used as an RF amplifier in the input stages of
    television sets working at about 45 Mc/s, so it can't have too bad >>>>>> a noise figure (although Mullard don't quote one in their data
    sheet). If I triode-strapped it and ran it in grounded grid mode, >>>>>> that would reduce the noise and increase the maximum frequency it >>>>>> could usefully amplify. From the data sheet, with 200v on anode and >>>>>> grid 2 and an anode current of 6mA, the gm is about 6mA/V, which >>>>>> gives an input impedance at the cathode of 160 ohms. A 75-ohm
    feeder could be matched to this with a Pi tank or by tapping the L >>>>>> or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in
    grounded cathode mode, but it allows the valve to be triode
    strapped for low noise without instability problems or the
    dependence on neutralising that a cascode stage would have
    (especially the need for correct neutralising to obtain the best >>>>>> noise figure). If I also use an EF91 as a mixer, I might need one >>>>>> more stage of RF gain to get the signal up to a level where the
    mixer noise is negligible - but this isn't such a bad thing because >>>>>> it would allow extra tuned circuits to give better image rejection >>>>>> and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up >>>> on the downlead. If the down-converter is adjacent to the HF
    receiver, there will be significant losses at VHF in the downlead, as >>>> the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>> signal could be radiated by the aerial - especially if it happens to lie >>>> at a frequency where the dipole has another resonance or the dipole and >>>> downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>> (the sleeve dipole has a 'cold' bottom end and could be joined directly >>>> onto the converter box). The HT and LT could be supplied either by a >>>> separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>> co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>> 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL
    handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group today who can really add any value here. Ham group, Liz; ham group.


    2 metres is pretty much DC nowadays anyhow.

    HF receivers don’t have to have good noise performance because the atmosphere is so noisy, and AFAICT they usually don’t. Intermod is more of an issue.

    The atmosphere is quieter above 100 MHz, though, so you care more about the Rx noise figure.

    A mixer front end is going to have a noise figure of 6 dB or so, on account of the conversion loss, and that adds to the NF of the HF back end.

    Some gain ahead of the mixer, and some more following the band select
    filter should help a lot. Don’t overdo it, of course.

    Thanks, that was the path my thoughts were going down. A grounded grid
    stage on a 200v HT supply should have reasonable linearity according to
    the data sheet. I hope to get a voltage gain of x10 from it from it if
    the anode circuit can be designed to be around 2 kilohms at resonance.
    That should lift the signal above the noise of the mixer stage with a
    bit to spare but still give good immunity to overloading.

    With one tuned circuit at the front and a slightly-overcoupled bandpass
    circuit to the mixer, the bandwidth over the band from 144 to 146 Mc/s
    should be fairly flat. Alternatively a bandpass troughline at the front
    and a single tuned anode load would give the same bandwidth and better out-of-band rejection ahead of the EF91.


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to Liz Tuddenham on Sun Nov 10 09:51:49 2024
    On Sat, 9 Nov 2024 21:40:06 +0000, Liz Tuddenham wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    [...]
    There's not a single person on this group today who can really add any
    value here.

    You do them a dis-service, there are some people here who can think with
    an open mind. Even if the ideas they come up with wouldn't work, trying
    to find out or explain why they wouldn't work is a good exercise and may
    lead to a better solution than just asking hams what they have done
    before.

    OK, that's entirely your call. But I think you'll find the number of
    people here with expertise in VHF receiver design is zero and the
    proportion of those with an adequate familiarity with designing for toobz
    is a vanishingly small subset of that figure. :)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to Jan Panteltje on Sun Nov 10 10:14:47 2024
    On Sun, 10 Nov 2024 06:08:27 GMT, Jan Panteltje wrote:

    On a sunny day (Sat, 9 Nov 2024 16:35:45 +0000) it happened liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in <1r2rj8l.msi28f14weovyN%liz@poppyrecords.invalid.invalid>:

    My current receiving aerial system is very inefficient at 2 metres (144 >>Mc/s) and I have thought about making a sleeve dipole for that band. My >>VHF receiver is an Eddystone 770R, which covers the band but only in a >>small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    Have you ever considered using a RTL_SDR stick and a PC or Raspberry
    program for reception?
    Something I wrote for it:
    https://panteltje.nl/pub/xpsa-0.7.gif
    those sticks cover from about 20 MHz to 1.6 GHz
    More abou those here:
    https://www.rtl-sdr.com/about-rtl-sdr/
    even used one to receive GPS signals Those sticks are about 40? dollars
    on ebay, accuracy 1 ppm.
    https://www.ebay.com/itm/276000566513?


    I'm sure Liz is aware there are far better modern alternatives out there,
    Jan. However, this is (I believe) a purely fun project - and I've been
    thinking for many years about doing a similar thing myself with tubes. In
    fact I've retained a substantial collection of the damn things for
    precisely this purpose. I always thought, 'one day I'll retire and I'll
    have time to build something using these valves and it'll be a blast.'
    Anyway, I retired 25 years ago and have even less time now for fun
    projects than I had when I was working. Such is life...


    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >>Stock, so that seems like a good valve to start playing about with.

    I remember ECC85 in FM tuners, should be fine at 144 MHz:
    https://www.radiomuseum.org/tubes/tube_ecc85.html

    That circuit diagram shows an about 100 MHz to 10.7 MHz FM radio input
    stage + mixer.
    I have used that tube a few times.

    But transistors took over, and now chips like in that RTL_SDR stick, are
    hard to beat.

    Sometimes I just strip some coax at the right length for antenna:
    https://www.panteltje.nl/pub/DVB-T2_antenna_IXIMG_0757.JPG
    Have some yagi antennas too, and even an old TV rack..
    And a big 27 MHz GPA antenna somewhere...

    Dunno if you have any of the RSGB-published books by Pat Hawker (G3VA
    IIRC) but he had several designs for very effective antennas at VHF and
    UHF made from lengths of old coax. The emphasis was always on economical designs with old Pat. He grew up in the shadow of WW2 where you had to
    make do with what you found lying around in the rubble of bomb craters.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Doom on Sun Nov 10 10:51:31 2024
    On a sunny day (Sun, 10 Nov 2024 09:51:49 -0000 (UTC)) it happened Cursitor Doom <cd999666@notformail.com> wrote in <vgpvnk$ao84$1@dont-email.me>:

    On Sat, 9 Nov 2024 21:40:06 +0000, Liz Tuddenham wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    [...]
    There's not a single person on this group today who can really add any
    value here.

    You do them a dis-service, there are some people here who can think with
    an open mind. Even if the ideas they come up with wouldn't work, trying
    to find out or explain why they wouldn't work is a good exercise and may
    lead to a better solution than just asking hams what they have done
    before.

    OK, that's entirely your call. But I think you'll find the number of
    people here with expertise in VHF receiver design is zero and the
    proportion of those with an adequate familiarity with designing for toobz
    is a vanishingly small subset of that figure. :)


    I designed plenty of VHF rx stuff, teefee works in that range,
    including UHF.
    But to go back in time and do it with toobs? No, I used transistors.
    Only case I could think of for using toobs is when all semi-conductors
    were destroyed by radiation.
    But not much would be on air to listen for in that case.
    And in that case shortwave would be a better place to listen for remaining lifeforms.
    And grounded grid does not make a lot of sense, has not many advantages for a VHF input stage.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Doom on Sun Nov 10 11:19:14 2024
    On a sunny day (Sun, 10 Nov 2024 10:14:47 -0000 (UTC)) it happened Cursitor Doom <cd999666@notformail.com> wrote in <vgq12n$ao84$2@dont-email.me>:

    On Sun, 10 Nov 2024 06:08:27 GMT, Jan Panteltje wrote:

    On a sunny day (Sat, 9 Nov 2024 16:35:45 +0000) it happened
    liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in
    <1r2rj8l.msi28f14weovyN%liz@poppyrecords.invalid.invalid>:

    My current receiving aerial system is very inefficient at 2 metres (144 >>>Mc/s) and I have thought about making a sleeve dipole for that band. My >>>VHF receiver is an Eddystone 770R, which covers the band but only in a >>>small portion of the whole scale. While I am improvomg the aerial >>>system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges >>>of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>scale length.

    Have you ever considered using a RTL_SDR stick and a PC or Raspberry
    program for reception?
    Something I wrote for it:
    https://panteltje.nl/pub/xpsa-0.7.gif
    those sticks cover from about 20 MHz to 1.6 GHz
    More abou those here:
    https://www.rtl-sdr.com/about-rtl-sdr/
    even used one to receive GPS signals Those sticks are about 40? dollars
    on ebay, accuracy 1 ppm.
    https://www.ebay.com/itm/276000566513?


    I'm sure Liz is aware there are far better modern alternatives out there, >Jan. However, this is (I believe) a purely fun project - and I've been >thinking for many years about doing a similar thing myself with tubes. In >fact I've retained a substantial collection of the damn things for
    precisely this purpose. I always thought, 'one day I'll retire and I'll
    have time to build something using these valves and it'll be a blast.' >Anyway, I retired 25 years ago and have even less time now for fun
    projects than I had when I was working. Such is life...

    When I had the teefee repair shop in Amsterdam in the seventies and early eighties
    lots of partial tube sets for repair, tubes especially in the HV stuff, PD500 makes a nice x-ray source:
    http://www.kronjaeger.com/hv-old/xray/tech/PD500/index.html
    had plenty tubes in stock,
    now I have zero tubes here...
    When I started in broadcasting in 1968 more tubes in the studios than you can imagine,
    https://www.historyofrecording.com/ampexvrx1000aniv.html
    note the racks with tubes in the picture on the left.


    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but >>>not necessarily the expensive 'cult' ones which everyone seems to regard >>>as having magical powers. The EF91 is plentiful and cheap as New Old >>>Stock, so that seems like a good valve to start playing about with.

    I remember ECC85 in FM tuners, should be fine at 144 MHz:
    https://www.radiomuseum.org/tubes/tube_ecc85.html

    That circuit diagram shows an about 100 MHz to 10.7 MHz FM radio input
    stage + mixer.
    I have used that tube a few times.

    But transistors took over, and now chips like in that RTL_SDR stick, are
    hard to beat.

    Sometimes I just strip some coax at the right length for antenna:
    https://www.panteltje.nl/pub/DVB-T2_antenna_IXIMG_0757.JPG
    Have some yagi antennas too, and even an old TV rack..
    And a big 27 MHz GPA antenna somewhere...

    Dunno if you have any of the RSGB-published books by Pat Hawker (G3VA
    IIRC) but he had several designs for very effective antennas at VHF and
    UHF made from lengths of old coax. The emphasis was always on economical >designs with old Pat. He grew up in the shadow of WW2 where you had to
    make do with what you found lying around in the rubble of bomb craters.

    I had a RSGB book, and in 1964-1967 period used it to design all that ham radio stuff..
    Very nice book, learned a lot from it.
    In the seventies in the studios more all transistor stuff,
    but still CRTs and film scanners with CRT to scan film with photo-multipliers for red green and blue,
    Not to mention the whole video camera stuff I worked with, evolving from inconoscope to plumbicons to CDD.
    Designed and build my own portable vidicon based TV camera in 1968, that gave me the broadcasting job basically.
    And that camera ran on nicad battery and was all transistor.

    We had nice electronic magazines too, 'Radio Electronica', 'Electuur' (Elector?)
    and whatever I could get hands on in English.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to All on Sun Nov 10 13:38:31 2024
    On Sun, 10 Nov 2024 11:19:14 GMT, Jan Panteltje <alien@comet.invalid>
    wrote:

    On a sunny day (Sun, 10 Nov 2024 10:14:47 -0000 (UTC)) it happened Cursitor >Doom <cd999666@notformail.com> wrote in <vgq12n$ao84$2@dont-email.me>:

    On Sun, 10 Nov 2024 06:08:27 GMT, Jan Panteltje wrote:

    On a sunny day (Sat, 9 Nov 2024 16:35:45 +0000) it happened
    liz@poppyrecords.invalid.invalid (Liz Tuddenham) wrote in
    <1r2rj8l.msi28f14weovyN%liz@poppyrecords.invalid.invalid>:

    My current receiving aerial system is very inefficient at 2 metres (144 >>>>Mc/s) and I have thought about making a sleeve dipole for that band. My >>>>VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>small portion of the whole scale. While I am improvomg the aerial >>>>system, I could also make a crystal-controlled down-converter, that >>>>would allow me to use an HF communications receiver or the lower ranges >>>>of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>scale length.

    Have you ever considered using a RTL_SDR stick and a PC or Raspberry
    program for reception?
    Something I wrote for it:
    https://panteltje.nl/pub/xpsa-0.7.gif
    those sticks cover from about 20 MHz to 1.6 GHz
    More abou those here:
    https://www.rtl-sdr.com/about-rtl-sdr/
    even used one to receive GPS signals Those sticks are about 40? dollars
    on ebay, accuracy 1 ppm.
    https://www.ebay.com/itm/276000566513?


    I'm sure Liz is aware there are far better modern alternatives out there, >>Jan. However, this is (I believe) a purely fun project - and I've been >>thinking for many years about doing a similar thing myself with tubes. In >>fact I've retained a substantial collection of the damn things for >>precisely this purpose. I always thought, 'one day I'll retire and I'll >>have time to build something using these valves and it'll be a blast.' >>Anyway, I retired 25 years ago and have even less time now for fun
    projects than I had when I was working. Such is life...

    When I had the teefee repair shop in Amsterdam in the seventies and early eighties
    lots of partial tube sets for repair, tubes especially in the HV stuff, PD500 makes a nice x-ray source:
    http://www.kronjaeger.com/hv-old/xray/tech/PD500/index.html
    had plenty tubes in stock,
    now I have zero tubes here...
    When I started in broadcasting in 1968 more tubes in the studios than you can imagine,
    https://www.historyofrecording.com/ampexvrx1000aniv.html
    note the racks with tubes in the picture on the left.


    It's been a few years since I designed anything with valves, so I >>>>thought I might have a go at making a down-converter using valves - but >>>>not necessarily the expensive 'cult' ones which everyone seems to regard >>>>as having magical powers. The EF91 is plentiful and cheap as New Old >>>>Stock, so that seems like a good valve to start playing about with.

    I remember ECC85 in FM tuners, should be fine at 144 MHz:
    https://www.radiomuseum.org/tubes/tube_ecc85.html

    That circuit diagram shows an about 100 MHz to 10.7 MHz FM radio input
    stage + mixer.
    I have used that tube a few times.

    But transistors took over, and now chips like in that RTL_SDR stick, are >>> hard to beat.

    Sometimes I just strip some coax at the right length for antenna:
    https://www.panteltje.nl/pub/DVB-T2_antenna_IXIMG_0757.JPG
    Have some yagi antennas too, and even an old TV rack..
    And a big 27 MHz GPA antenna somewhere...

    Dunno if you have any of the RSGB-published books by Pat Hawker (G3VA
    IIRC) but he had several designs for very effective antennas at VHF and
    UHF made from lengths of old coax. The emphasis was always on economical >>designs with old Pat. He grew up in the shadow of WW2 where you had to
    make do with what you found lying around in the rubble of bomb craters.

    I had a RSGB book, and in 1964-1967 period used it to design all that ham radio stuff..
    Very nice book, learned a lot from it.
    In the seventies in the studios more all transistor stuff,
    but still CRTs and film scanners with CRT to scan film with photo-multipliers for red green and blue,
    Not to mention the whole video camera stuff I worked with, evolving from inconoscope to plumbicons to CDD.
    Designed and build my own portable vidicon based TV camera in 1968, that gave me the broadcasting job basically.
    And that camera ran on nicad battery and was all transistor.

    We had nice electronic magazines too, 'Radio Electronica', 'Electuur' (Elector?)
    and whatever I could get hands on in English.

    Elektor was one of the better hobby ones. I was also subscribed to
    Wireless World which was a bit more heavy-duty. No idea if any of
    these are still being published and can't be bothered to find out.
    There was also Everyday Electronics and Practical Electronics, too.
    I'm guessing they've all gone now since the kids just want to code it
    seems.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ralph Mowery@21:1/5 to All on Sun Nov 10 09:33:05 2024
    In article <1r2sqh1.puusef1eope1aN%liz@poppyrecords.invalid.invalid>, liz@poppyrecords.invalid.invalid says...


    Tubes are noisy. There are MMICS with NFs below 1 dB.

    There are quiet valves (Nuvistors) and noisy transistors (many),
    engineering is a matter of chosing the right ones or using them in a way which minimises the noise or makes it less significant in the overall
    design.



    Once you get above say 100 MHz the tubes that are common do not have the
    noise figure of very cheap solid state devices. A nuvistor at 150 MHz
    will do good to prodce a noise figure of 3 dB. A cheap fet like a U310
    will have a noise figure of less than 2 dB and the power supply will be
    much cheaper to build. Going to cheap gasfets get you to under 1 dB of
    noise figure. At this time I just do not see why anyone would want to
    use tubes in a receiver above 50 MHz if they want a sensitive receiver.

    Years ago I had an Ameco receive converter for 2 meters. It used
    nuvistor tubes. Worked fine but I put a u310 fet preamp on it and it
    was noticable beter.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to cd@notformail.com on Sun Nov 10 14:33:41 2024
    On a sunny day (Sun, 10 Nov 2024 13:38:31 +0000) it happened Cursitor Doom <cd@notformail.com> wrote in <eld1jjl15hq8ohgm3kifpodkktupt1lr3g@4ax.com>:

    On Sun, 10 Nov 2024 11:19:14 GMT, Jan Panteltje <alien@comet.invalid>
    wrote:
    ...
    We had nice electronic magazines too, 'Radio Electronica', 'Electuur' (Elector?)
    and whatever I could get hands on in English.

    Elektor was one of the better hobby ones. I was also subscribed to
    Wireless World which was a bit more heavy-duty.

    Yes I used to read that on occasion (if I did see it at the newsstand at the staion for example)
    plus some German electronic related magazines,


    No idea if any of
    these are still being published and can't be bothered to find out.
    There was also Everyday Electronics and Practical Electronics, too.
    I'm guessing they've all gone now since the kids just want to code it
    seems.

    Na, there is still a lot around on hardware design / building stuff, several websites.
    Just google works great too.

    Electronics is used in a very wide field...
    Just got a new alu housing with fan for my raspi 4 8 GB (this one I use to post this)
    It has an IR camera connected too (mlx90640_FLIR),
    now to find a way to get the i2c and power lines to that IR camera module
    out of that housing...

    What bothers me today (thought maybe use an extra Raspberry Pi) is that prices are going up to insane lavels for a Raspi5 8 Gb + supply + housing + sdcard to above 120 USD:
    https://www.sossolutions.nl/raspberry-pi-5-8gb-starter-kit-compleet

    For just a bit more you have a decent mini computer:
    https://www.aliexpress.com/w/wholesale-mini-pc-x86.html

    Inflation?
    Time to end raspi stuff and look for other solutions.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Ralph Mowery@21:1/5 to All on Sun Nov 10 09:46:36 2024
    In article <vgop30$in7$1@dont-email.me>,
    pcdhSpamMeSenseless@electrooptical.net says...

    HF receivers don?t have to have good noise performance because the
    atmosphere is so noisy, and AFAICT they usually don?t. Intermod is more of an issue.




    That is very true. I have a 60 year old tube receiver and up to 10 MHz
    I can hear any signal on it as I can on my year old Icom 7610. However
    the modern receiver does much better selecting a signal when there are
    many signals on the band. My 50 year old Heathkit tube and transistor
    receivers work just as well up to 30 MHz as the Icom as far as hearing a
    weak signal if there are no strong stations near by.

    It does not do much good to have a receiver with a sensitivity of .1 uV
    when there is a noise of 1 uV all aound you if not more.

    With all the man made noise in many locations 50 MHz is getting to be
    very noisey and 150 MHz is starting to get that way.
    At one time I had a modem that put out a signal that was strong enough
    to lock up my scanning receiver on one of the 2 meter repeaters I used.
    I was out in the country and not much around to give problesm but my own
    house.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From piglet@21:1/5 to Phil Hobbs on Sun Nov 10 14:59:29 2024
    On 09/11/2024 22:52, Phil Hobbs wrote:
    Cursitor Doom <cd@notformail.com> wrote:
    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >>>>>> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144 >>>>>>> Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>>>> small portion of the whole scale. While I am improvomg the aerial >>>>>>> system, I could also make a crystal-controlled down-converter, that >>>>>>> would allow me to use an HF communications receiver or the lower ranges >>>>>>> of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>>>> scale length.

    It's been a few years since I designed anything with valves, so I >>>>>>> thought I might have a go at making a down-converter using valves - but >>>>>>> not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >>>>>>> Stock, so that seems like a good valve to start playing about with. >>>>>>>
    The EF91 was used as an RF amplifier in the input stages of television >>>>>>> sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>>>>> (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>>>>> the noise and increase the maximum frequency it could usefully amplify. >>>>>>> From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the >>>>>>> cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>>>>> Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded
    cathode mode, but it allows the valve to be triode strapped for low >>>>>>> noise without instability problems or the dependence on neutralising >>>>>>> that a cascode stage would have (especially the need for correct >>>>>>> neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to >>>>>>> a level where the mixer noise is negligible - but this isn't such a bad >>>>>>> thing because it would allow extra tuned circuits to give better image >>>>>>> rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on >>>>> the downlead. If the down-converter is adjacent to the HF receiver, >>>>> there will be significant losses at VHF in the downlead, as the aerial >>>>> needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>>> signal could be radiated by the aerial - especially if it happens to lie >>>>> at a frequency where the dipole has another resonance or the dipole and >>>>> downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>>> (the sleeve dipole has a 'cold' bottom end and could be joined directly >>>>> onto the converter box). The HT and LT could be supplied either by a >>>>> separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>>> co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>>> 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL
    handbooks. If you have any from the early 60s lying around it should
    be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group
    today who can really add any value here. Ham group, Liz; ham group.


    2 metres is pretty much DC nowadays anyhow.

    HF receivers don’t have to have good noise performance because the atmosphere is so noisy, and AFAICT they usually don’t. Intermod is more of an issue.

    The atmosphere is quieter above 100 MHz, though, so you care more about the Rx noise figure.

    A mixer front end is going to have a noise figure of 6 dB or so, on account of the conversion loss, and that adds to the NF of the HF back end.

    Some gain ahead of the mixer, and some more following the band select
    filter should help a lot. Don’t overdo it, of course.

    Cheers

    Phil Hobbs



    Remarkably commutating switch mixer like diode rings etc can be made
    almost lossless if the source and load impedances are manipulated right. British ham Peter Martinez the inventor of varicode psk31 has shown that
    if the mixer RF port is fed from a parallel tuned circuit and IF port
    loaded with a series tuned circuit in the right ratio then the 6dB loss
    always assumed to be unavoidable goes.

    piglet

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to rmowery42@charter.net on Sun Nov 10 07:42:35 2024
    On Sun, 10 Nov 2024 09:33:05 -0500, Ralph Mowery
    <rmowery42@charter.net> wrote:

    In article <1r2sqh1.puusef1eope1aN%liz@poppyrecords.invalid.invalid>, >liz@poppyrecords.invalid.invalid says...


    Tubes are noisy. There are MMICS with NFs below 1 dB.

    There are quiet valves (Nuvistors) and noisy transistors (many),
    engineering is a matter of chosing the right ones or using them in a way
    which minimises the noise or makes it less significant in the overall
    design.



    Once you get above say 100 MHz the tubes that are common do not have the >noise figure of very cheap solid state devices. A nuvistor at 150 MHz
    will do good to prodce a noise figure of 3 dB. A cheap fet like a U310
    will have a noise figure of less than 2 dB and the power supply will be
    much cheaper to build. Going to cheap gasfets get you to under 1 dB of
    noise figure. At this time I just do not see why anyone would want to
    use tubes in a receiver above 50 MHz if they want a sensitive receiver.

    Years ago I had an Ameco receive converter for 2 meters. It used
    nuvistor tubes. Worked fine but I put a u310 fet preamp on it and it
    was noticable beter.

    A cheap MMIC from MiniCircuits will get down to 1 dB, and it's 4 pins,
    in out 2 grounds, fabulously simple.

    I use their MMICS in time domain, as pulse amplifiers. Most - not all
    - work fine down to DC. As is some Federal law with RF parts, the DC
    specs are absurd so you have to characterize them yourself.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to Liz Tuddenham on Sun Nov 10 07:33:15 2024
    On Sun, 10 Nov 2024 08:00:17 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres
    (144 Mc/s) and I have thought about making a sleeve dipole for that >> >> >> >band. My VHF receiver is an Eddystone 770R, which covers the band
    but only in a small portion of the whole scale. While I am
    improvomg the aerial system, I could also make a crystal-controlled >> >> >> >down-converter, that would allow me to use an HF communications
    receiver or the lower ranges of the 770R, so that the band 2 Mc/s
    wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - >> >> >> >but not necessarily the expensive 'cult' ones which everyone seems
    to regard as having magical powers. The EF91 is plentiful and
    cheap as New Old Stock, so that seems like a good valve to start
    playing about with.

    The EF91 was used as an RF amplifier in the input stages of
    television sets working at about 45 Mc/s, so it can't have too bad
    a noise figure (although Mullard don't quote one in their data
    sheet). If I triode-strapped it and ran it in grounded grid mode,
    that would reduce the noise and increase the maximum frequency it
    could usefully amplify. From the data sheet, with 200v on anode and >> >> >> >grid 2 and an anode current of 6mA, the gm is about 6mA/V, which
    gives an input impedance at the cathode of 160 ohms. A 75-ohm
    feeder could be matched to this with a Pi tank or by tapping the L
    or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in
    grounded cathode mode, but it allows the valve to be triode
    strapped for low noise without instability problems or the
    dependence on neutralising that a cascode stage would have
    (especially the need for correct neutralising to obtain the best
    noise figure). If I also use an EF91 as a mixer, I might need one
    more stage of RF gain to get the signal up to a level where the
    mixer noise is negligible - but this isn't such a bad thing because >> >> >> >it would allow extra tuned circuits to give better image rejection
    and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up
    on the downlead. If the down-converter is adjacent to the HF
    receiver, there will be significant losses at VHF in the downlead, as
    the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local
    oscillator signal could be radiated by the aerial - especially if it
    happens to lie at a frequency where the dipole has another resonance
    or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the
    aerial (the sleeve dipole has a 'cold' bottom end and could be joined
    directly onto the converter box). The HT and LT could be supplied
    either by a separate multi-core cable or by superimposing 40v A.C. at >> >> >50c/s on the co-ax and feeding it into the 200-220-240v tappings.of a
    mains transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v
    or 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due respect >> >> - will be able to assist you very much in this endeavour. However,
    there should be tons of info on this in one of the old ARRL handbooks.
    If you have any from the early 60s lying around it should be well worth >> >> a look through.

    I have read most of that sort of literature in the past and still have
    copies of most of it but don't remember this particular approach being
    used before - that was why I though it might make a good fun project.
    There are some grounded-grid circuits but they use triodes intended for
    the purpose. There are cascode circuits with double (and sometimes two
    single) triodes but, again, the triodes are intended for that purpose.
    The idea of using a bog-standard descendent of the ubiquitous EF50 for
    frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a
    triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the
    wideband front end of a noise-measuring set that I designed; it gave very >> >satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact -
    comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low
    value resistor, a Q killer.

    Series-tuned input circuit.

    Or a parallel tank with taps. The Q killers are the radiation
    resistance of the antenna and, a little bit, the ohmic component of
    the grid impedance from electrons being ornery.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to All on Sun Nov 10 07:47:32 2024
    On Sun, 10 Nov 2024 14:59:29 +0000, piglet <erichpwagner@hotmail.com>
    wrote:

    On 09/11/2024 22:52, Phil Hobbs wrote:
    Cursitor Doom <cd@notformail.com> wrote:
    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >>>>>>> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144
    Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>>>>> small portion of the whole scale. While I am improvomg the aerial >>>>>>>> system, I could also make a crystal-controlled down-converter, that >>>>>>>> would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>>>>> scale length.

    It's been a few years since I designed anything with valves, so I >>>>>>>> thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >>>>>>>> Stock, so that seems like a good valve to start playing about with. >>>>>>>>
    The EF91 was used as an RF amplifier in the input stages of television >>>>>>>> sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>>>>>> (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>>>>>> the noise and increase the maximum frequency it could usefully amplify.
    From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the >>>>>>>> cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>>>>>> Pi tank or by tapping the L or the C of an input tumed circuit. >>>>>>>>
    The voltage gain may not be as high in this configuration as in grounded
    cathode mode, but it allows the valve to be triode strapped for low >>>>>>>> noise without instability problems or the dependence on neutralising >>>>>>>> that a cascode stage would have (especially the need for correct >>>>>>>> neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad
    thing because it would allow extra tuned circuits to give better image >>>>>>>> rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves? >>>>>>>

    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>>>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on >>>>>> the downlead. If the down-converter is adjacent to the HF receiver, >>>>>> there will be significant losses at VHF in the downlead, as the aerial >>>>>> needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>>>> signal could be radiated by the aerial - especially if it happens to lie >>>>>> at a frequency where the dipole has another resonance or the dipole and >>>>>> downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>>>> (the sleeve dipole has a 'cold' bottom end and could be joined directly >>>>>> onto the converter box). The HT and LT could be supplied either by a >>>>>> separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>>>> co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>>>> 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL >>>>> handbooks. If you have any from the early 60s lying around it should >>>>> be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group
    today who can really add any value here. Ham group, Liz; ham group.


    2 metres is pretty much DC nowadays anyhow.

    HF receivers don’t have to have good noise performance because the
    atmosphere is so noisy, and AFAICT they usually don’t. Intermod is more of >> an issue.

    The atmosphere is quieter above 100 MHz, though, so you care more about the >> Rx noise figure.

    A mixer front end is going to have a noise figure of 6 dB or so, on account >> of the conversion loss, and that adds to the NF of the HF back end.

    Some gain ahead of the mixer, and some more following the band select
    filter should help a lot. Don’t overdo it, of course.

    Cheers

    Phil Hobbs



    Remarkably commutating switch mixer like diode rings etc can be made
    almost lossless if the source and load impedances are manipulated right. >British ham Peter Martinez the inventor of varicode psk31 has shown that
    if the mixer RF port is fed from a parallel tuned circuit and IF port
    loaded with a series tuned circuit in the right ratio then the 6dB loss >always assumed to be unavoidable goes.

    piglet

    If a mixer is just made of switches (diodes, phemts, relays) there is
    no loss mechanism.

    You do get sum and difference outputs, but any single mixer does that.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to john larkin on Sun Nov 10 16:03:25 2024
    john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 08:00:17 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >> >> >> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres >> >> >> >(144 Mc/s) and I have thought about making a sleeve dipole for that >> >> >> >band. My VHF receiver is an Eddystone 770R, which covers the band >> >> >> >but only in a small portion of the whole scale. While I am
    improvomg the aerial system, I could also make a crystal-controlled >> >> >> >down-converter, that would allow me to use an HF communications
    receiver or the lower ranges of the 770R, so that the band 2 Mc/s >> >> >> >wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I >> >> >> >thought I might have a go at making a down-converter using valves - >> >> >> >but not necessarily the expensive 'cult' ones which everyone seems >> >> >> >to regard as having magical powers. The EF91 is plentiful and
    cheap as New Old Stock, so that seems like a good valve to start
    playing about with.

    The EF91 was used as an RF amplifier in the input stages of
    television sets working at about 45 Mc/s, so it can't have too bad >> >> >> >a noise figure (although Mullard don't quote one in their data
    sheet). If I triode-strapped it and ran it in grounded grid mode, >> >> >> >that would reduce the noise and increase the maximum frequency it >> >> >> >could usefully amplify. From the data sheet, with 200v on anode and >> >> >> >grid 2 and an anode current of 6mA, the gm is about 6mA/V, which
    gives an input impedance at the cathode of 160 ohms. A 75-ohm
    feeder could be matched to this with a Pi tank or by tapping the L >> >> >> >or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in
    grounded cathode mode, but it allows the valve to be triode
    strapped for low noise without instability problems or the
    dependence on neutralising that a cascode stage would have
    (especially the need for correct neutralising to obtain the best
    noise figure). If I also use an EF91 as a mixer, I might need one >> >> >> >more stage of RF gain to get the signal up to a level where the
    mixer noise is negligible - but this isn't such a bad thing because >> >> >> >it would allow extra tuned circuits to give better image rejection >> >> >> >and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up >> >> >on the downlead. If the down-converter is adjacent to the HF
    receiver, there will be significant losses at VHF in the downlead, as >> >> >the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local
    oscillator signal could be radiated by the aerial - especially if it >> >> >happens to lie at a frequency where the dipole has another resonance >> >> >or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the
    aerial (the sleeve dipole has a 'cold' bottom end and could be joined >> >> >directly onto the converter box). The HT and LT could be supplied
    either by a separate multi-core cable or by superimposing 40v A.C. at >> >> >50c/s on the co-ax and feeding it into the 200-220-240v tappings.of a >> >> >mains transformer primary. The full primary winding would act as an >> >> >auto-transformer to give 250v H.T. and the secondary could give 6.3v >> >> >or 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due respect >> >> - will be able to assist you very much in this endeavour. However,
    there should be tons of info on this in one of the old ARRL handbooks. >> >> If you have any from the early 60s lying around it should be well worth >> >> a look through.

    I have read most of that sort of literature in the past and still have
    copies of most of it but don't remember this particular approach being
    used before - that was why I though it might make a good fun project.
    There are some grounded-grid circuits but they use triodes intended for >> >the purpose. There are cascode circuits with double (and sometimes two >> >single) triodes but, again, the triodes are intended for that purpose. >> >The idea of using a bog-standard descendent of the ubiquitous EF50 for
    frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a
    triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the >> >wideband front end of a noise-measuring set that I designed; it gave very >> >satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact -
    comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low
    value resistor, a Q killer.

    Series-tuned input circuit.

    Or a parallel tank with taps. The Q killers are the radiation
    resistance of the antenna and, a little bit, the ohmic component of
    the grid impedance from electrons being ornery.

    The point I was making about grounded-grid operation is that the input impedance of the valve is very nearly the characteristic impedance of
    the co-ax (voltage ratio 3:2 for a triode-strapped EF91 drawing 6mA from
    a 200V HT line). A Pi network or a 3:2 winding on a ferrite core could
    be used to match them

    With some VHF triodes, the gm is around 13 mA/V so the ratio is 1:1
    without any additional matching componments and you can join the cathode through an isolation capacitor directly to the aerial socket, if you
    don't mind the lack of selectivity..

    If you want selectivity, insert a series-tuned circuit which will be
    high impedance to unwanted frequencies and low impedance to the wanted
    ones. The input impedance of the valve and the characteristic impedance
    of the feeder and dipole appear in series as the resistive component of
    the series tuned circuit, so the lower they are, the higher will be the
    'Q'.

    Another possibility is to use two EF91s in parallel to bring the
    impedance down to 80 ohms. The phasing errors between different valves
    is unlikely to be significant at 144 Mc/s.


    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to All on Sun Nov 10 17:33:01 2024
    On Sun, 10 Nov 2024 14:59:29 +0000, piglet <erichpwagner@hotmail.com>
    wrote:

    On 09/11/2024 22:52, Phil Hobbs wrote:
    Cursitor Doom <cd@notformail.com> wrote:
    On Sat, 09 Nov 2024 12:21:41 -0800, john larkin <JL@gct.com> wrote:

    On Sat, 09 Nov 2024 20:02:05 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >>>>>>> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres (144
    Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a >>>>>>>> small portion of the whole scale. While I am improvomg the aerial >>>>>>>> system, I could also make a crystal-controlled down-converter, that >>>>>>>> would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater >>>>>>>> scale length.

    It's been a few years since I designed anything with valves, so I >>>>>>>> thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >>>>>>>> Stock, so that seems like a good valve to start playing about with. >>>>>>>>
    The EF91 was used as an RF amplifier in the input stages of television >>>>>>>> sets working at about 45 Mc/s, so it can't have too bad a noise figure >>>>>>>> (although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce >>>>>>>> the noise and increase the maximum frequency it could usefully amplify.
    From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the >>>>>>>> cathode of 160 ohms. A 75-ohm feeder could be matched to this with a >>>>>>>> Pi tank or by tapping the L or the C of an input tumed circuit. >>>>>>>>
    The voltage gain may not be as high in this configuration as in grounded
    cathode mode, but it allows the valve to be triode strapped for low >>>>>>>> noise without instability problems or the dependence on neutralising >>>>>>>> that a cascode stage would have (especially the need for correct >>>>>>>> neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad
    thing because it would allow extra tuned circuits to give better image >>>>>>>> rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves? >>>>>>>

    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that atmospheric >>>>>>> noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up on >>>>>> the downlead. If the down-converter is adjacent to the HF receiver, >>>>>> there will be significant losses at VHF in the downlead, as the aerial >>>>>> needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local oscillator >>>>>> signal could be radiated by the aerial - especially if it happens to lie >>>>>> at a frequency where the dipole has another resonance or the dipole and >>>>>> downlead form a resonant system.

    I was thinking in terms of the converter being right next to the aerial >>>>>> (the sleeve dipole has a 'cold' bottom end and could be joined directly >>>>>> onto the converter box). The HT and LT could be supplied either by a >>>>>> separate multi-core cable or by superimposing 40v A.C. at 50c/s on the >>>>>> co-ax and feeding it into the 200-220-240v tappings.of a mains
    transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v or >>>>>> 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due
    respect - will be able to assist you very much in this endeavour.
    However, there should be tons of info on this in one of the old ARRL >>>>> handbooks. If you have any from the early 60s lying around it should >>>>> be well worth a look through.

    I was never interested in rag chewing, but signals is still signals.

    Indeed, but this is niche and there are so many fine points and
    trade-offs and gotchas that need to be factored in that only a
    dedicated VHF RF designer could assist here. For sure the best people
    here could come up with a workable design, but in practice it would
    stink for the above reasons. There's not a single person on this group
    today who can really add any value here. Ham group, Liz; ham group.


    2 metres is pretty much DC nowadays anyhow.

    HF receivers don’t have to have good noise performance because the
    atmosphere is so noisy, and AFAICT they usually don’t. Intermod is more of >> an issue.

    The atmosphere is quieter above 100 MHz, though, so you care more about the >> Rx noise figure.

    A mixer front end is going to have a noise figure of 6 dB or so, on account >> of the conversion loss, and that adds to the NF of the HF back end.

    Some gain ahead of the mixer, and some more following the band select
    filter should help a lot. Don’t overdo it, of course.

    Cheers

    Phil Hobbs



    Remarkably commutating switch mixer like diode rings etc can be made
    almost lossless if the source and load impedances are manipulated right. >British ham Peter Martinez the inventor of varicode psk31 has shown that
    if the mixer RF port is fed from a parallel tuned circuit and IF port
    loaded with a series tuned circuit in the right ratio then the 6dB loss >always assumed to be unavoidable goes.


    Sounds like a band pass filter you're describing here, mon cher
    piglet.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to All on Sun Nov 10 17:39:36 2024
    On Sun, 10 Nov 2024 14:33:41 GMT, Jan Panteltje <alien@comet.invalid>
    wrote:

    On a sunny day (Sun, 10 Nov 2024 13:38:31 +0000) it happened Cursitor Doom ><cd@notformail.com> wrote in <eld1jjl15hq8ohgm3kifpodkktupt1lr3g@4ax.com>:

    On Sun, 10 Nov 2024 11:19:14 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:
    ...
    We had nice electronic magazines too, 'Radio Electronica', 'Electuur' (Elector?)
    and whatever I could get hands on in English.

    Elektor was one of the better hobby ones. I was also subscribed to
    Wireless World which was a bit more heavy-duty.

    Yes I used to read that on occasion (if I did see it at the newsstand at the staion for example)
    plus some German electronic related magazines,


    No idea if any of
    these are still being published and can't be bothered to find out.
    There was also Everyday Electronics and Practical Electronics, too.
    I'm guessing they've all gone now since the kids just want to code it >>seems.

    Na, there is still a lot around on hardware design / building stuff, several websites.
    Just google works great too.

    Electronics is used in a very wide field...
    Just got a new alu housing with fan for my raspi 4 8 GB (this one I use to post this)
    It has an IR camera connected too (mlx90640_FLIR),
    now to find a way to get the i2c and power lines to that IR camera module
    out of that housing...

    What bothers me today (thought maybe use an extra Raspberry Pi) is that prices >are going up to insane lavels for a Raspi5 8 Gb + supply + housing + sdcard to above 120 USD:
    https://www.sossolutions.nl/raspberry-pi-5-8gb-starter-kit-compleet

    For just a bit more you have a decent mini computer:
    https://www.aliexpress.com/w/wholesale-mini-pc-x86.html

    Inflation?
    Time to end raspi stuff and look for other solutions.


    Arduinos are very cheap and don't have all the overhead the Pi has in
    terms of video capabilities. Plus they're piss-easy to program.
    A Pi 5 plus accessories for 120 bux doesn't sound bad at all, though.
    Or if you're really that much of a skinflint, you could consider PIC programming. :-)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to Jan Panteltje on Sun Nov 10 12:23:37 2024
    "Jan Panteltje" <alien@comet.invalid> wrote in message news:vgq37s$oo9h$1@solani.org...
    On a sunny day (Sun, 10 Nov 2024 09:51:49 -0000 (UTC)) it happened Cursitor Doom <cd999666@notformail.com> wrote in <vgpvnk$ao84$1@dont-email.me>:

    On Sat, 9 Nov 2024 21:40:06 +0000, Liz Tuddenham wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    [...]
    There's not a single person on this group today who can really add any >>>> value here.

    You do them a dis-service, there are some people here who can think with >>> an open mind. Even if the ideas they come up with wouldn't work, trying >>> to find out or explain why they wouldn't work is a good exercise and may >>> lead to a better solution than just asking hams what they have done
    before.

    OK, that's entirely your call. But I think you'll find the number of
    people here with expertise in VHF receiver design is zero and the >>proportion of those with an adequate familiarity with designing for toobz >>is a vanishingly small subset of that figure. :)


    I designed plenty of VHF rx stuff, teefee works in that range,
    including UHF.
    But to go back in time and do it with toobs? No, I used transistors.
    Only case I could think of for using toobs is when all semi-conductors
    were destroyed by radiation.
    But not much would be on air to listen for in that case.
    And in that case shortwave would be a better place to listen for remaining lifeforms.
    And grounded grid does not make a lot of sense, has not many advantages for a VHF input stage.

    Why?
    https://www.google.com/search?&q=valve+fm+tuner&udm=2
    I can see at least two grounded grids and I don't recall a transistor FM tuner without a grounded base first stage.
    Reduced sensitivity was ofted caused by a need to replace that transistor because being the first stage it gets what the antenna
    gets.



    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to Liz Tuddenham on Sun Nov 10 10:09:22 2024
    On Sun, 10 Nov 2024 16:03:25 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 08:00:17 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid >> >> >> >> (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres >> >> >> >> >(144 Mc/s) and I have thought about making a sleeve dipole for that
    band. My VHF receiver is an Eddystone 770R, which covers the band >> >> >> >> >but only in a small portion of the whole scale. While I am
    improvomg the aerial system, I could also make a crystal-controlled
    down-converter, that would allow me to use an HF communications
    receiver or the lower ranges of the 770R, so that the band 2 Mc/s >> >> >> >> >wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I >> >> >> >> >thought I might have a go at making a down-converter using valves -
    but not necessarily the expensive 'cult' ones which everyone seems >> >> >> >> >to regard as having magical powers. The EF91 is plentiful and
    cheap as New Old Stock, so that seems like a good valve to start >> >> >> >> >playing about with.

    The EF91 was used as an RF amplifier in the input stages of
    television sets working at about 45 Mc/s, so it can't have too bad >> >> >> >> >a noise figure (although Mullard don't quote one in their data
    sheet). If I triode-strapped it and ran it in grounded grid mode, >> >> >> >> >that would reduce the noise and increase the maximum frequency it >> >> >> >> >could usefully amplify. From the data sheet, with 200v on anode and
    grid 2 and an anode current of 6mA, the gm is about 6mA/V, which >> >> >> >> >gives an input impedance at the cathode of 160 ohms. A 75-ohm
    feeder could be matched to this with a Pi tank or by tapping the L >> >> >> >> >or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in
    grounded cathode mode, but it allows the valve to be triode
    strapped for low noise without instability problems or the
    dependence on neutralising that a cascode stage would have
    (especially the need for correct neutralising to obtain the best >> >> >> >> >noise figure). If I also use an EF91 as a mixer, I might need one >> >> >> >> >more stage of RF gain to get the signal up to a level where the
    mixer noise is negligible - but this isn't such a bad thing because
    it would allow extra tuned circuits to give better image rejection >> >> >> >> >and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves? >> >> >> >>

    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up >> >> >> >on the downlead. If the down-converter is adjacent to the HF
    receiver, there will be significant losses at VHF in the downlead, as >> >> >> >the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local
    oscillator signal could be radiated by the aerial - especially if it >> >> >> >happens to lie at a frequency where the dipole has another resonance >> >> >> >or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the
    aerial (the sleeve dipole has a 'cold' bottom end and could be joined >> >> >> >directly onto the converter box). The HT and LT could be supplied
    either by a separate multi-core cable or by superimposing 40v A.C. at
    50c/s on the co-ax and feeding it into the 200-220-240v tappings.of a >> >> >> >mains transformer primary. The full primary winding would act as an >> >> >> >auto-transformer to give 250v H.T. and the secondary could give 6.3v >> >> >> >or 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due respect
    - will be able to assist you very much in this endeavour. However,
    there should be tons of info on this in one of the old ARRL handbooks. >> >> >> If you have any from the early 60s lying around it should be well worth
    a look through.

    I have read most of that sort of literature in the past and still have >> >> >copies of most of it but don't remember this particular approach being >> >> >used before - that was why I though it might make a good fun project.
    There are some grounded-grid circuits but they use triodes intended for >> >> >the purpose. There are cascode circuits with double (and sometimes two >> >> >single) triodes but, again, the triodes are intended for that purpose. >> >> >The idea of using a bog-standard descendent of the ubiquitous EF50 for >> >> >frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a
    triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the >> >> >wideband front end of a noise-measuring set that I designed; it gave very
    satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact -
    comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low
    value resistor, a Q killer.

    Series-tuned input circuit.

    Or a parallel tank with taps. The Q killers are the radiation
    resistance of the antenna and, a little bit, the ohmic component of
    the grid impedance from electrons being ornery.

    The point I was making about grounded-grid operation is that the input >impedance of the valve is very nearly the characteristic impedance of
    the co-ax (voltage ratio 3:2 for a triode-strapped EF91 drawing 6mA from
    a 200V HT line). A Pi network or a 3:2 winding on a ferrite core could
    be used to match them

    A tuned circuit into the grid has voltage gain, but the grounded-grid
    with ohmic matched impedance throws away at least half the available
    signal voltage. Impedance matching isn't good when it throws away
    signal.

    It's the voltage difference between the grid and cathode that gets
    amplified against the tube's inherent noise.

    Of course you can never get a better s/n than what the antenna
    provides, and that will be pretty bad, so working hard to get a very
    low noise fig in a HF receiver is entertaining but not terribly
    useful.

    At some wavelengths, in the microwave, looking at things way overhead
    with a very directional antenna, low noise figures are worth the
    hassle. The effective temperature of the universe is low.

    A very directional antenna is a big win on s/n. It ignores a lot of
    junk. I don't think it improves the inherent thermal background if
    it's receiving terrestrial transmitters. That would violate COE.

    I wonder if one can tell the difference in thermal noise by aiming an
    antenna north or south from the USA or Europe. It's certainly less
    aiming up.

    I guess a good antenna feeding a matched resistive load will heat up
    the load; steal power from the BBC. Or aim up and cool it.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to john larkin on Sun Nov 10 18:14:33 2024
    On Sun, 10 Nov 2024 10:09:22 -0800, john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 16:03:25 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 08:00:17 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid >>> >> >> (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres
    (144 Mc/s) and I have thought about making a sleeve dipole for that
    band. My VHF receiver is an Eddystone 770R, which covers the band
    but only in a small portion of the whole scale. While I am
    improvomg the aerial system, I could also make a crystal-controlled
    down-converter, that would allow me to use an HF communications >>> >> >> >> >receiver or the lower ranges of the 770R, so that the band 2 Mc/s
    wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I >>> >> >> >> >thought I might have a go at making a down-converter using valves -
    but not necessarily the expensive 'cult' ones which everyone seems
    to regard as having magical powers. The EF91 is plentiful and >>> >> >> >> >cheap as New Old Stock, so that seems like a good valve to start >>> >> >> >> >playing about with.

    The EF91 was used as an RF amplifier in the input stages of
    television sets working at about 45 Mc/s, so it can't have too bad
    a noise figure (although Mullard don't quote one in their data >>> >> >> >> >sheet). If I triode-strapped it and ran it in grounded grid mode,
    that would reduce the noise and increase the maximum frequency it >>> >> >> >> >could usefully amplify. From the data sheet, with 200v on anode and
    grid 2 and an anode current of 6mA, the gm is about 6mA/V, which >>> >> >> >> >gives an input impedance at the cathode of 160 ohms. A 75-ohm >>> >> >> >> >feeder could be matched to this with a Pi tank or by tapping the L
    or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in >>> >> >> >> >grounded cathode mode, but it allows the valve to be triode
    strapped for low noise without instability problems or the
    dependence on neutralising that a cascode stage would have
    (especially the need for correct neutralising to obtain the best >>> >> >> >> >noise figure). If I also use an EF91 as a mixer, I might need one
    more stage of RF gain to get the signal up to a level where the >>> >> >> >> >mixer noise is negligible - but this isn't such a bad thing because
    it would allow extra tuned circuits to give better image rejection
    and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves? >>> >> >> >>

    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF
    receiver is almost certain to suffer from strong HF signals picked up
    on the downlead. If the down-converter is adjacent to the HF
    receiver, there will be significant losses at VHF in the downlead, as
    the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local
    oscillator signal could be radiated by the aerial - especially if it >>> >> >> >happens to lie at a frequency where the dipole has another resonance >>> >> >> >or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the
    aerial (the sleeve dipole has a 'cold' bottom end and could be joined
    directly onto the converter box). The HT and LT could be supplied >>> >> >> >either by a separate multi-core cable or by superimposing 40v A.C. at
    50c/s on the co-ax and feeding it into the 200-220-240v tappings.of a
    mains transformer primary. The full primary winding would act as an >>> >> >> >auto-transformer to give 250v H.T. and the secondary could give 6.3v >>> >> >> >or 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due respect
    - will be able to assist you very much in this endeavour. However, >>> >> >> there should be tons of info on this in one of the old ARRL handbooks.
    If you have any from the early 60s lying around it should be well worth
    a look through.

    I have read most of that sort of literature in the past and still have >>> >> >copies of most of it but don't remember this particular approach being >>> >> >used before - that was why I though it might make a good fun project. >>> >> >There are some grounded-grid circuits but they use triodes intended for >>> >> >the purpose. There are cascode circuits with double (and sometimes two >>> >> >single) triodes but, again, the triodes are intended for that purpose. >>> >> >The idea of using a bog-standard descendent of the ubiquitous EF50 for >>> >> >frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a
    triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the >>> >> >wideband front end of a noise-measuring set that I designed; it gave very
    satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact -
    comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low
    value resistor, a Q killer.

    Series-tuned input circuit.

    Or a parallel tank with taps. The Q killers are the radiation
    resistance of the antenna and, a little bit, the ohmic component of
    the grid impedance from electrons being ornery.

    The point I was making about grounded-grid operation is that the input >>impedance of the valve is very nearly the characteristic impedance of
    the co-ax (voltage ratio 3:2 for a triode-strapped EF91 drawing 6mA from
    a 200V HT line). A Pi network or a 3:2 winding on a ferrite core could
    be used to match them

    A tuned circuit into the grid has voltage gain, but the grounded-grid
    with ohmic matched impedance throws away at least half the available
    signal voltage. Impedance matching isn't good when it throws away
    signal.

    It's the voltage difference between the grid and cathode that gets
    amplified against the tube's inherent noise.

    Of course you can never get a better s/n than what the antenna
    provides, and that will be pretty bad, so working hard to get a very
    low noise fig in a HF receiver is entertaining but not terribly
    useful.

    At some wavelengths, in the microwave, looking at things way overhead
    with a very directional antenna, low noise figures are worth the
    hassle. The effective temperature of the universe is low.

    A very directional antenna is a big win on s/n. It ignores a lot of
    junk. I don't think it improves the inherent thermal background if
    it's receiving terrestrial transmitters. That would violate COE.

    I wonder if one can tell the difference in thermal noise by aiming an
    antenna north or south from the USA or Europe. It's certainly less
    aiming up.

    I guess a good antenna feeding a matched resistive load will heat up
    the load; steal power from the BBC. Or aim up and cool it.

    Under 5Mhz is where it gets particularly bad. 80m is often unusable.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to All on Sun Nov 10 11:11:48 2024
    On Sun, 10 Nov 2024 18:14:33 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sun, 10 Nov 2024 10:09:22 -0800, john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 16:03:25 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 08:00:17 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid >>>> >> (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid >>>> >> >> (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres
    (144 Mc/s) and I have thought about making a sleeve dipole for that
    band. My VHF receiver is an Eddystone 770R, which covers the band
    but only in a small portion of the whole scale. While I am
    improvomg the aerial system, I could also make a crystal-controlled
    down-converter, that would allow me to use an HF communications >>>> >> >> >> >receiver or the lower ranges of the 770R, so that the band 2 Mc/s
    wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves -
    but not necessarily the expensive 'cult' ones which everyone seems
    to regard as having magical powers. The EF91 is plentiful and >>>> >> >> >> >cheap as New Old Stock, so that seems like a good valve to start >>>> >> >> >> >playing about with.

    The EF91 was used as an RF amplifier in the input stages of
    television sets working at about 45 Mc/s, so it can't have too bad
    a noise figure (although Mullard don't quote one in their data >>>> >> >> >> >sheet). If I triode-strapped it and ran it in grounded grid mode,
    that would reduce the noise and increase the maximum frequency it
    could usefully amplify. From the data sheet, with 200v on anode and
    grid 2 and an anode current of 6mA, the gm is about 6mA/V, which >>>> >> >> >> >gives an input impedance at the cathode of 160 ohms. A 75-ohm >>>> >> >> >> >feeder could be matched to this with a Pi tank or by tapping the L
    or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in >>>> >> >> >> >grounded cathode mode, but it allows the valve to be triode
    strapped for low noise without instability problems or the
    dependence on neutralising that a cascode stage would have
    (especially the need for correct neutralising to obtain the best >>>> >> >> >> >noise figure). If I also use an EF91 as a mixer, I might need one
    more stage of RF gain to get the signal up to a level where the >>>> >> >> >> >mixer noise is negligible - but this isn't such a bad thing because
    it would allow extra tuned circuits to give better image rejection
    and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves? >>>> >> >> >>

    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF >>>> >> >> >receiver is almost certain to suffer from strong HF signals picked up
    on the downlead. If the down-converter is adjacent to the HF
    receiver, there will be significant losses at VHF in the downlead, as
    the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local
    oscillator signal could be radiated by the aerial - especially if it
    happens to lie at a frequency where the dipole has another resonance
    or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the >>>> >> >> >aerial (the sleeve dipole has a 'cold' bottom end and could be joined
    directly onto the converter box). The HT and LT could be supplied >>>> >> >> >either by a separate multi-core cable or by superimposing 40v A.C. at
    50c/s on the co-ax and feeding it into the 200-220-240v tappings.of a
    mains transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v
    or 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due respect
    - will be able to assist you very much in this endeavour. However, >>>> >> >> there should be tons of info on this in one of the old ARRL handbooks.
    If you have any from the early 60s lying around it should be well worth
    a look through.

    I have read most of that sort of literature in the past and still have >>>> >> >copies of most of it but don't remember this particular approach being >>>> >> >used before - that was why I though it might make a good fun project. >>>> >> >There are some grounded-grid circuits but they use triodes intended for
    the purpose. There are cascode circuits with double (and sometimes two
    single) triodes but, again, the triodes are intended for that purpose.
    The idea of using a bog-standard descendent of the ubiquitous EF50 for >>>> >> >frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a >>>> >> >triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the
    wideband front end of a noise-measuring set that I designed; it gave very
    satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact - >>>> >> comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low
    value resistor, a Q killer.

    Series-tuned input circuit.

    Or a parallel tank with taps. The Q killers are the radiation
    resistance of the antenna and, a little bit, the ohmic component of
    the grid impedance from electrons being ornery.

    The point I was making about grounded-grid operation is that the input >>>impedance of the valve is very nearly the characteristic impedance of
    the co-ax (voltage ratio 3:2 for a triode-strapped EF91 drawing 6mA from >>>a 200V HT line). A Pi network or a 3:2 winding on a ferrite core could >>>be used to match them

    A tuned circuit into the grid has voltage gain, but the grounded-grid
    with ohmic matched impedance throws away at least half the available
    signal voltage. Impedance matching isn't good when it throws away
    signal.

    It's the voltage difference between the grid and cathode that gets >>amplified against the tube's inherent noise.

    Of course you can never get a better s/n than what the antenna
    provides, and that will be pretty bad, so working hard to get a very
    low noise fig in a HF receiver is entertaining but not terribly
    useful.

    At some wavelengths, in the microwave, looking at things way overhead
    with a very directional antenna, low noise figures are worth the
    hassle. The effective temperature of the universe is low.

    A very directional antenna is a big win on s/n. It ignores a lot of
    junk. I don't think it improves the inherent thermal background if
    it's receiving terrestrial transmitters. That would violate COE.

    I wonder if one can tell the difference in thermal noise by aiming an >>antenna north or south from the USA or Europe. It's certainly less
    aiming up.

    I guess a good antenna feeding a matched resistive load will heat up
    the load; steal power from the BBC. Or aim up and cool it.

    Under 5Mhz is where it gets particularly bad. 80m is often unusable.

    Again, a very directional antenna will help a lot. I guess that's
    tricky at 80m, but some sort of phased array with signal processing
    would be interesting.

    Hasn't cell phones and the internet made ham radio and shortwave
    listening mostly obsolete? Are kids becoming hams?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to john larkin on Sun Nov 10 19:33:39 2024
    john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 16:03:25 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:
    [...]

    The point I was making about grounded-grid operation is that the input >impedance of the valve is very nearly the characteristic impedance of
    the co-ax (voltage ratio 3:2 for a triode-strapped EF91 drawing 6mA from
    a 200V HT line). A Pi network or a 3:2 winding on a ferrite core could
    be used to match them

    A tuned circuit into the grid has voltage gain,

    It's about power noise and power gain, not voltage noise and voltage
    gain., a tuned circuit doesn't have power gain. At lower impedances the
    noise voltage and the signal voltage are reduced equally so the S/N
    power ratio isn't altered. Matching the feeder and aerial impedance to
    the circuit impedance is what matters, that wsy you get maximum signal
    power transfer.

    Grounded grid circuits were common above 150 Mc/s and gave good S/N
    ratios, the reason they weren't much used below that frequency was
    because specialised valves in conventional circuits could do the job adequately. I am trying to push a general purpose valve to do the job
    of a specialised one. (Like a BC109 being used as a VHF oscillator - it
    can work if you get it right!)

    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to john larkin on Sun Nov 10 20:17:08 2024
    On Sun, 10 Nov 2024 11:11:48 -0800, john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 18:14:33 +0000, Cursitor Doom <cd@notformail.com>
    wrote:

    On Sun, 10 Nov 2024 10:09:22 -0800, john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 16:03:25 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 08:00:17 +0000, liz@poppyrecords.invalid.invalid >>>>> (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid >>>>> >> (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid >>>>> >> >> (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres
    (144 Mc/s) and I have thought about making a sleeve dipole for that
    band. My VHF receiver is an Eddystone 770R, which covers the band
    but only in a small portion of the whole scale. While I am >>>>> >> >> >> >improvomg the aerial system, I could also make a crystal-controlled
    down-converter, that would allow me to use an HF communications >>>>> >> >> >> >receiver or the lower ranges of the 770R, so that the band 2 Mc/s
    wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves -
    but not necessarily the expensive 'cult' ones which everyone seems
    to regard as having magical powers. The EF91 is plentiful and >>>>> >> >> >> >cheap as New Old Stock, so that seems like a good valve to start
    playing about with.

    The EF91 was used as an RF amplifier in the input stages of >>>>> >> >> >> >television sets working at about 45 Mc/s, so it can't have too bad
    a noise figure (although Mullard don't quote one in their data >>>>> >> >> >> >sheet). If I triode-strapped it and ran it in grounded grid mode,
    that would reduce the noise and increase the maximum frequency it
    could usefully amplify. From the data sheet, with 200v on anode and
    grid 2 and an anode current of 6mA, the gm is about 6mA/V, which
    gives an input impedance at the cathode of 160 ohms. A 75-ohm >>>>> >> >> >> >feeder could be matched to this with a Pi tank or by tapping the L
    or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in >>>>> >> >> >> >grounded cathode mode, but it allows the valve to be triode >>>>> >> >> >> >strapped for low noise without instability problems or the >>>>> >> >> >> >dependence on neutralising that a cascode stage would have >>>>> >> >> >> >(especially the need for correct neutralising to obtain the best
    noise figure). If I also use an EF91 as a mixer, I might need one
    more stage of RF gain to get the signal up to a level where the >>>>> >> >> >> >mixer noise is negligible - but this isn't such a bad thing because
    it would allow extra tuned circuits to give better image rejection
    and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?


    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF >>>>> >> >> >receiver is almost certain to suffer from strong HF signals picked up
    on the downlead. If the down-converter is adjacent to the HF >>>>> >> >> >receiver, there will be significant losses at VHF in the downlead, as
    the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local >>>>> >> >> >oscillator signal could be radiated by the aerial - especially if it
    happens to lie at a frequency where the dipole has another resonance
    or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the >>>>> >> >> >aerial (the sleeve dipole has a 'cold' bottom end and could be joined
    directly onto the converter box). The HT and LT could be supplied >>>>> >> >> >either by a separate multi-core cable or by superimposing 40v A.C. at
    50c/s on the co-ax and feeding it into the 200-220-240v tappings.of a
    mains transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v
    or 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due respect
    - will be able to assist you very much in this endeavour. However, >>>>> >> >> there should be tons of info on this in one of the old ARRL handbooks.
    If you have any from the early 60s lying around it should be well worth
    a look through.

    I have read most of that sort of literature in the past and still have
    copies of most of it but don't remember this particular approach being
    used before - that was why I though it might make a good fun project. >>>>> >> >There are some grounded-grid circuits but they use triodes intended for
    the purpose. There are cascode circuits with double (and sometimes two
    single) triodes but, again, the triodes are intended for that purpose.
    The idea of using a bog-standard descendent of the ubiquitous EF50 for
    frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff >>>>> >> >Woodburn's design for the Eddystone Panoramic Display Unit, where a >>>>> >> >triode-strapped E180F is used as a grounded-grid untuned wideband >>>>> >> >front-end amplifier. I did copy that successfully with a ZTX450 as the
    wideband front end of a noise-measuring set that I designed; it gave very
    satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact - >>>>> >> comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low >>>>> >> value resistor, a Q killer.

    Series-tuned input circuit.

    Or a parallel tank with taps. The Q killers are the radiation
    resistance of the antenna and, a little bit, the ohmic component of
    the grid impedance from electrons being ornery.

    The point I was making about grounded-grid operation is that the input >>>>impedance of the valve is very nearly the characteristic impedance of >>>>the co-ax (voltage ratio 3:2 for a triode-strapped EF91 drawing 6mA from >>>>a 200V HT line). A Pi network or a 3:2 winding on a ferrite core could >>>>be used to match them

    A tuned circuit into the grid has voltage gain, but the grounded-grid >>>with ohmic matched impedance throws away at least half the available >>>signal voltage. Impedance matching isn't good when it throws away
    signal.

    It's the voltage difference between the grid and cathode that gets >>>amplified against the tube's inherent noise.

    Of course you can never get a better s/n than what the antenna
    provides, and that will be pretty bad, so working hard to get a very
    low noise fig in a HF receiver is entertaining but not terribly
    useful.

    At some wavelengths, in the microwave, looking at things way overhead >>>with a very directional antenna, low noise figures are worth the
    hassle. The effective temperature of the universe is low.

    A very directional antenna is a big win on s/n. It ignores a lot of
    junk. I don't think it improves the inherent thermal background if
    it's receiving terrestrial transmitters. That would violate COE.

    I wonder if one can tell the difference in thermal noise by aiming an >>>antenna north or south from the USA or Europe. It's certainly less
    aiming up.

    I guess a good antenna feeding a matched resistive load will heat up
    the load; steal power from the BBC. Or aim up and cool it.

    Under 5Mhz is where it gets particularly bad. 80m is often unusable.

    Again, a very directional antenna will help a lot. I guess that's
    tricky at 80m, but some sort of phased array with signal processing
    would be interesting.

    Hasn't cell phones and the internet made ham radio and shortwave
    listening mostly obsolete? Are kids becoming hams?

    Ham radio seems to be alive and well AFAIK, despite very few kids
    getting into it currently. Curiously, Morse code is still extremely
    popular and has very many adherents, some of whom spend a small
    fortune on fancy keys. Speeds have gone up massively over the last
    half century and I struggle to copy much of what's being sent nowadays
    it's become so fast.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to invalid@invalid.invalid on Mon Nov 11 06:18:35 2024
    On a sunny day (Sun, 10 Nov 2024 12:23:37 -0500) it happened "Edward Rawde" <invalid@invalid.invalid> wrote in <vgqq6p$1red$1@nnrp.usenet.blueworldhosting.com>:

    "Jan Panteltje" <alien@comet.invalid> wrote in message news:vgq37s$oo9h$1@solani.org...
    On a sunny day (Sun, 10 Nov 2024 09:51:49 -0000 (UTC)) it happened Cursitor >> Doom <cd999666@notformail.com> wrote in <vgpvnk$ao84$1@dont-email.me>:

    On Sat, 9 Nov 2024 21:40:06 +0000, Liz Tuddenham wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    [...]
    There's not a single person on this group today who can really add any >>>>> value here.

    You do them a dis-service, there are some people here who can think with >>>> an open mind. Even if the ideas they come up with wouldn't work, trying >>>> to find out or explain why they wouldn't work is a good exercise and may >>>> lead to a better solution than just asking hams what they have done
    before.

    OK, that's entirely your call. But I think you'll find the number of >>>people here with expertise in VHF receiver design is zero and the >>>proportion of those with an adequate familiarity with designing for toobz >>>is a vanishingly small subset of that figure. :)


    I designed plenty of VHF rx stuff, teefee works in that range,
    including UHF.
    But to go back in time and do it with toobs? No, I used transistors.
    Only case I could think of for using toobs is when all semi-conductors
    were destroyed by radiation.
    But not much would be on air to listen for in that case.
    And in that case shortwave would be a better place to listen for remaining lifeforms.
    And grounded grid does not make a lot of sense, has not many advantages for a VHF input stage.

    Why?
    https://www.google.com/search?&q=valve+fm+tuner&udm=2
    I can see at least two grounded grids and I don't recall a transistor FM tuner without a grounded base first stage.
    Reduced sensitivity was ofted caused by a need to replace that transistor because being the first stage it gets what the antenna

    Sure it exists, there are also people walking on their hands.
    This for example is an over-complicated mess:
    https://www.google.com/search?q=valve+fm+tuner&tbm=isch#imgrc=yLFnU8USesQRNM

    Also complicated but grid input:
    https://www.maximus-randd.com/uploads/2/4/4/5/24459638/philips-receiving-tubes-for-fm-schema-i_orig.jpg


    This was more like the normal:
    https://www.vintage-radio.net/forum/attachment.php?attachmentid=73886&d=1355353510

    But explain to me tha advantage of the grounded grid setup, always ready to learn something!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to cd@notformail.com on Mon Nov 11 06:38:13 2024
    On a sunny day (Sun, 10 Nov 2024 17:39:36 +0000) it happened Cursitor Doom <cd@notformail.com> wrote in <qpr1jj9glcibtukfkhsgt3m0ujq0kkho0l@4ax.com>:

    On Sun, 10 Nov 2024 14:33:41 GMT, Jan Panteltje <alien@comet.invalid>
    wrote:

    On a sunny day (Sun, 10 Nov 2024 13:38:31 +0000) it happened Cursitor Doom >><cd@notformail.com> wrote in <eld1jjl15hq8ohgm3kifpodkktupt1lr3g@4ax.com>:

    On Sun, 10 Nov 2024 11:19:14 GMT, Jan Panteltje <alien@comet.invalid> >>>wrote:
    ...
    We had nice electronic magazines too, 'Radio Electronica', 'Electuur' (Elector?)
    and whatever I could get hands on in English.

    Elektor was one of the better hobby ones. I was also subscribed to >>>Wireless World which was a bit more heavy-duty.

    Yes I used to read that on occasion (if I did see it at the newsstand at the staion for example)
    plus some German electronic related magazines,


    No idea if any of
    these are still being published and can't be bothered to find out.
    There was also Everyday Electronics and Practical Electronics, too.
    I'm guessing they've all gone now since the kids just want to code it >>>seems.

    Na, there is still a lot around on hardware design / building stuff, several websites.
    Just google works great too.

    Electronics is used in a very wide field...
    Just got a new alu housing with fan for my raspi 4 8 GB (this one I use to post this)
    It has an IR camera connected too (mlx90640_FLIR),
    now to find a way to get the i2c and power lines to that IR camera module >>out of that housing...

    What bothers me today (thought maybe use an extra Raspberry Pi) is that prices
    are going up to insane lavels for a Raspi5 8 Gb + supply + housing + sdcard to above 120 USD:
    https://www.sossolutions.nl/raspberry-pi-5-8gb-starter-kit-compleet

    For just a bit more you have a decent mini computer:
    https://www.aliexpress.com/w/wholesale-mini-pc-x86.html

    Inflation?
    Time to end raspi stuff and look for other solutions.


    Arduinos are very cheap and don't have all the overhead the Pi has in
    terms of video capabilities. Plus they're piss-easy to program.
    A Pi 5 plus accessories for 120 bux doesn't sound bad at all, though.
    Or if you're really that much of a skinflint, you could consider PIC >programming. :-)

    I use this Pi 4 8 GB for web browsing, posting stuff here, spectrum analyzer, radio reception , music play, so much more
    An arduno is something totally different.
    But this 4 8GB is dead slow at times browsing the web.
    Added a metal case with fan now to prevent it from throtling on over-temperature
    so now its hovers around
    temp=40.9'C
    temp=41.3'C
    temp=40.4'
    ..
    Just cut and paste

    Has a 4 TB Toshiba harddisc connected to it, some RTL-SDR stick, A huawei 4G stick so I have internet on it,
    a HDMI monitor, and for all the other USB stuff a Sitecom USB hub, a Logitech wireless keyboard... and that IR FLIR camera on GPIO.

    raspberrypi: ~ # df
    Filesystem 1K-blocks Used Available Use% Mounted on
    /dev/root 30421240 27643352 1432704 96% /
    devtmpfs 3879380 0 3879380 0% /dev
    tmpfs 4044244 0 4044244 0% /dev/shm
    tmpfs 1617700 1336 1616364 1% /run
    tmpfs 5120 4 5116 1% /run/lock
    /dev/mmcblk0p1 258095 50413 207682 20% /boot
    tmpfs 808848 24 808824 1% /run/user/1000
    /dev/sda2 3844420600 2863079020 785980916 79% /mnt/sda2

    raspberrypi: ~ # top
    top - 07:27:40 up 1 day, 22:12, 11 users, load average: 0.64, 0.66, 0.97 Tasks: 221 total, 1 running, 220 sleeping, 0 stopped, 0 zombie
    %Cpu(s): 4.8 us, 4.3 sy, 0.0 ni, 90.8 id, 0.1 wa, 0.0 hi, 0.1 si, 0.0 st MiB Mem : 7898.9 total, 6529.0 free, 727.2 used, 642.7 buff/cache
    MiB Swap: 100.0 total, 100.0 free, 0.0 used. 6853.9 avail Mem
    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
    1105 root 19 -1 195056 77668 56360 S 10.2 1.0 195:49.13 Xorg
    12594 root 20 0 980792 351696 161036 S 6.6 4.3 7:45.00 firefox-esr
    12782 root 20 0 496732 164380 94644 S 3.9 2.0 2:14.18 Web Content
    1123 root 20 0 48028 12892 8604 S 1.6 0.2 0:01.86 rxvt
    1219 root 20 0 6644 4208 3832 S 1.6 0.1 37:20.43 xosview 12732 root 20 0 640868 135868 81320 S 1.3 1.7 1:02.58 WebExtensions
    ....


    As to PIC programming, how about a simple oscilloscope with FFT option:
    https://panteltje.nl/panteltje/pic/scope_pic/
    from
    https://panteltje.nl/panteltje/pic/index.html
    Or controlling a drone:
    https://panteltje.nl/panteltje/quadcopter/index.html
    From:
    https://panteltje.nl/panteltje/newsflex/download.html

    and now show us somthing YOU designed, code YOU wrote, THAT WORKS!
    And stop meddling here as if you are a censor, Billy blacklisting game with J Lurking
    This is a non-moderated group, bring in some more content than boat anchors and show us!

    !

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to cd@notformail.com on Mon Nov 11 06:50:30 2024
    On a sunny day (Sun, 10 Nov 2024 18:14:33 +0000) it happened Cursitor Doom <cd@notformail.com> wrote in <fut1jj1utr9u2nrgtp7q1fmnagk6v47js1@4ax.com>:

    On Sun, 10 Nov 2024 10:09:22 -0800, john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 16:03:25 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sun, 10 Nov 2024 08:00:17 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 20:26:18 +0000, liz@poppyrecords.invalid.invalid >>>> >> (Liz Tuddenham) wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    On Sat, 9 Nov 2024 19:27:13 +0000, liz@poppyrecords.invalid.invalid >>>> >> >> (Liz Tuddenham) wrote:

    john larkin <JL@gct.com> wrote:

    On Sat, 9 Nov 2024 16:35:45 +0000, liz@poppyrecords.invalid.invalid
    (Liz Tuddenham) wrote:

    My current receiving aerial system is very inefficient at 2 metres
    (144 Mc/s) and I have thought about making a sleeve dipole for that
    band. My VHF receiver is an Eddystone 770R, which covers the band
    but only in a small portion of the whole scale. While I am
    improvomg the aerial system, I could also make a crystal-controlled
    down-converter, that would allow me to use an HF communications >>>> >> >> >> >receiver or the lower ranges of the 770R, so that the band 2 Mc/s
    wide would cover a much greater scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves -
    but not necessarily the expensive 'cult' ones which everyone seems
    to regard as having magical powers. The EF91 is plentiful and >>>> >> >> >> >cheap as New Old Stock, so that seems like a good valve to start >>>> >> >> >> >playing about with.

    The EF91 was used as an RF amplifier in the input stages of
    television sets working at about 45 Mc/s, so it can't have too bad
    a noise figure (although Mullard don't quote one in their data >>>> >> >> >> >sheet). If I triode-strapped it and ran it in grounded grid mode,
    that would reduce the noise and increase the maximum frequency it
    could usefully amplify. From the data sheet, with 200v on anode and
    grid 2 and an anode current of 6mA, the gm is about 6mA/V, which >>>> >> >> >> >gives an input impedance at the cathode of 160 ohms. A 75-ohm >>>> >> >> >> >feeder could be matched to this with a Pi tank or by tapping the L
    or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in >>>> >> >> >> >grounded cathode mode, but it allows the valve to be triode
    strapped for low noise without instability problems or the
    dependence on neutralising that a cascode stage would have
    (especially the need for correct neutralising to obtain the best >>>> >> >> >> >noise figure). If I also use an EF91 as a mixer, I might need one
    more stage of RF gain to get the signal up to a level where the >>>> >> >> >> >mixer noise is negligible - but this isn't such a bad thing because
    it would allow extra tuned circuits to give better image rejection
    and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves? >>>> >> >> >>

    How about a tube/valve XO and a diode mixer to start?

    A good HF receiver may have a low enough noise figure that
    atmospheric noise still dominates.

    Good thinking but there are several snags with that system:

    If the down-converter is at the aerial end of the feeder, the HF >>>> >> >> >receiver is almost certain to suffer from strong HF signals picked up
    on the downlead. If the down-converter is adjacent to the HF
    receiver, there will be significant losses at VHF in the downlead, as
    the aerial needs to be mounted as high as possible.

    If there is no amplifier ahead of the mixing diode, the local
    oscillator signal could be radiated by the aerial - especially if it
    happens to lie at a frequency where the dipole has another resonance
    or the dipole and downlead form a resonant system.

    I was thinking in terms of the converter being right next to the >>>> >> >> >aerial (the sleeve dipole has a 'cold' bottom end and could be joined
    directly onto the converter box). The HT and LT could be supplied >>>> >> >> >either by a separate multi-core cable or by superimposing 40v A.C. at
    50c/s on the co-ax and feeding it into the 200-220-240v tappings.of a
    mains transformer primary. The full primary winding would act as an
    auto-transformer to give 250v H.T. and the secondary could give 6.3v
    or 12.6v to run the heaters.

    This is really ham territory so I don't think JL - with all due respect
    - will be able to assist you very much in this endeavour. However, >>>> >> >> there should be tons of info on this in one of the old ARRL handbooks.
    If you have any from the early 60s lying around it should be well worth
    a look through.

    I have read most of that sort of literature in the past and still have >>>> >> >copies of most of it but don't remember this particular approach being >>>> >> >used before - that was why I though it might make a good fun project. >>>> >> >There are some grounded-grid circuits but they use triodes intended for
    the purpose. There are cascode circuits with double (and sometimes two
    single) triodes but, again, the triodes are intended for that purpose.
    The idea of using a bog-standard descendent of the ubiquitous EF50 for >>>> >> >frequencies it wasn't supposed to cover - and making it do that
    adequately - appealed to me.

    The only place I have come across anything like this is in Geoff
    Woodburn's design for the Eddystone Panoramic Display Unit, where a >>>> >> >triode-strapped E180F is used as a grounded-grid untuned wideband
    front-end amplifier. I did copy that successfully with a ZTX450 as the
    wideband front end of a noise-measuring set that I designed; it gave very
    satisfactory results.

    Seems to me that the lowest noise voltage gain - no noise in fact - >>>> >> comes from a high-Q LC resonator. And that best drives a small
    capacitance like a grid.

    Driving a cathode can be wideband, but a cathode looks like a low
    value resistor, a Q killer.

    Series-tuned input circuit.

    Or a parallel tank with taps. The Q killers are the radiation
    resistance of the antenna and, a little bit, the ohmic component of
    the grid impedance from electrons being ornery.

    The point I was making about grounded-grid operation is that the input >>>impedance of the valve is very nearly the characteristic impedance of
    the co-ax (voltage ratio 3:2 for a triode-strapped EF91 drawing 6mA from >>>a 200V HT line). A Pi network or a 3:2 winding on a ferrite core could >>>be used to match them

    A tuned circuit into the grid has voltage gain, but the grounded-grid
    with ohmic matched impedance throws away at least half the available
    signal voltage. Impedance matching isn't good when it throws away
    signal.

    It's the voltage difference between the grid and cathode that gets >>amplified against the tube's inherent noise.

    Of course you can never get a better s/n than what the antenna
    provides, and that will be pretty bad, so working hard to get a very
    low noise fig in a HF receiver is entertaining but not terribly
    useful.

    At some wavelengths, in the microwave, looking at things way overhead
    with a very directional antenna, low noise figures are worth the
    hassle. The effective temperature of the universe is low.

    A very directional antenna is a big win on s/n. It ignores a lot of
    junk. I don't think it improves the inherent thermal background if
    it's receiving terrestrial transmitters. That would violate COE.

    I wonder if one can tell the difference in thermal noise by aiming an >>antenna north or south from the USA or Europe. It's certainly less
    aiming up.

    I guess a good antenna feeding a matched resistive load will heat up
    the load; steal power from the BBC. Or aim up and cool it.

    Under 5Mhz is where it gets particularly bad. 80m is often unusable.

    I do seem to have an atenna tuner somewhere
    https://panteltje.nl/pub/ebay_QRP_antenna_tuner_IXIMG_0552.JPG
    Not usd much till now...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From brian@21:1/5 to Liz Tuddenham on Mon Nov 11 14:14:39 2024
    In message <1r2rj8l.msi28f14weovyN%liz@poppyrecords.invalid.invalid>,
    Liz Tuddenham <liz@poppyrecords.invalid.invalid> writes
    My current receiving aerial system is very inefficient at 2 metres (144
    Mc/s) and I have thought about making a sleeve dipole for that band. My
    VHF receiver is an Eddystone 770R, which covers the band but only in a
    small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old
    Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television
    sets working at about 45 Mc/s, so it can't have too bad a noise figure >(although Mullard don't quote one in their data sheet). If I
    triode-strapped it and ran it in grounded grid mode, that would reduce
    the noise and increase the maximum frequency it could usefully amplify.
    From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the
    cathode of 160 ohms. A 75-ohm feeder could be matched to this with a
    Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct
    neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad
    thing because it would allow extra tuned circuits to give better image >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?



    I built a 2metre down converter in 1971. It used an E88CC ( gold pins!)
    cascode grounded grid front end followed by an ECC81 mixer. Another
    ECC81 was used as xtal Local Oscillator/multiplier.

    I still have it.

    The design was in UK publication Practical Wireless. I had quick look on
    World Radio History to see if I could find it , but no joy. Similar
    designs might be available.

    Brian





    --
    Brian Howie

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Liz Tuddenham@21:1/5 to brian on Mon Nov 11 17:26:19 2024
    brian <nospam@b-howie.co.uk> wrote:

    In message <1r2rj8l.msi28f14weovyN%liz@poppyrecords.invalid.invalid>,
    Liz Tuddenham <liz@poppyrecords.invalid.invalid> writes
    My current receiving aerial system is very inefficient at 2 metres (144 >Mc/s) and I have thought about making a sleeve dipole for that band. My >VHF receiver is an Eddystone 770R, which covers the band but only in a >small portion of the whole scale. While I am improvomg the aerial
    system, I could also make a crystal-controlled down-converter, that
    would allow me to use an HF communications receiver or the lower ranges
    of the 770R, so that the band 2 Mc/s wide would cover a much greater
    scale length.

    It's been a few years since I designed anything with valves, so I
    thought I might have a go at making a down-converter using valves - but
    not necessarily the expensive 'cult' ones which everyone seems to regard
    as having magical powers. The EF91 is plentiful and cheap as New Old >Stock, so that seems like a good valve to start playing about with.

    The EF91 was used as an RF amplifier in the input stages of television
    sets working at about 45 Mc/s, so it can't have too bad a noise figure >(although Mullard don't quote one in their data sheet). If I >triode-strapped it and ran it in grounded grid mode, that would reduce
    the noise and increase the maximum frequency it could usefully amplify. >From the data sheet, with 200v on anode and grid 2 and an anode current
    of 6mA, the gm is about 6mA/V, which gives an input impedance at the >cathode of 160 ohms. A 75-ohm feeder could be matched to this with a
    Pi tank or by tapping the L or the C of an input tumed circuit.

    The voltage gain may not be as high in this configuration as in grounded >cathode mode, but it allows the valve to be triode strapped for low
    noise without instability problems or the dependence on neutralising
    that a cascode stage would have (especially the need for correct >neutralising to obtain the best noise figure). If I also use an EF91 as
    a mixer, I might need one more stage of RF gain to get the signal up to
    a level where the mixer noise is negligible - but this isn't such a bad >thing because it would allow extra tuned circuits to give better image >rejection and allow a lower output frquency if I wanted one.

    Anyone with experience of doing something like this with valves?



    I built a 2metre down converter in 1971. It used an E88CC ( gold pins!) cascode grounded grid front end followed by an ECC81 mixer. Another
    ECC81 was used as xtal Local Oscillator/multiplier.

    I still have it.

    The design was in UK publication Practical Wireless. I had quick look on World Radio History to see if I could find it , but no joy. Similar
    designs might be available.

    I've found one similar to your description in the VHF/UHF Manual by
    Jessop, published by the RSGB. Knowing Practical Wireless, the version
    you saw was probably copied from there and published under the name of a notorious electronics 'guru' with a few component changes (not usually
    for the better).

    --
    ~ Liz Tuddenham ~
    (Remove the ".invalid"s and add ".co.uk" to reply)
    www.poppyrecords.co.uk

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to All on Mon Nov 11 22:42:50 2024
    On Mon, 11 Nov 2024 06:38:13 GMT, Jan Panteltje <alien@comet.invalid>
    wrote:

    On a sunny day (Sun, 10 Nov 2024 17:39:36 +0000) it happened Cursitor Doom ><cd@notformail.com> wrote in <qpr1jj9glcibtukfkhsgt3m0ujq0kkho0l@4ax.com>:

    On Sun, 10 Nov 2024 14:33:41 GMT, Jan Panteltje <alien@comet.invalid> >>wrote:

    On a sunny day (Sun, 10 Nov 2024 13:38:31 +0000) it happened Cursitor Doom >>><cd@notformail.com> wrote in <eld1jjl15hq8ohgm3kifpodkktupt1lr3g@4ax.com>: >>>
    On Sun, 10 Nov 2024 11:19:14 GMT, Jan Panteltje <alien@comet.invalid> >>>>wrote:
    ...
    We had nice electronic magazines too, 'Radio Electronica', 'Electuur' (Elector?)
    and whatever I could get hands on in English.

    Elektor was one of the better hobby ones. I was also subscribed to >>>>Wireless World which was a bit more heavy-duty.

    Yes I used to read that on occasion (if I did see it at the newsstand at the staion for example)
    plus some German electronic related magazines,


    No idea if any of
    these are still being published and can't be bothered to find out. >>>>There was also Everyday Electronics and Practical Electronics, too.
    I'm guessing they've all gone now since the kids just want to code it >>>>seems.

    Na, there is still a lot around on hardware design / building stuff, several websites.
    Just google works great too.

    Electronics is used in a very wide field...
    Just got a new alu housing with fan for my raspi 4 8 GB (this one I use to post this)
    It has an IR camera connected too (mlx90640_FLIR),
    now to find a way to get the i2c and power lines to that IR camera module >>>out of that housing...

    What bothers me today (thought maybe use an extra Raspberry Pi) is that prices
    are going up to insane lavels for a Raspi5 8 Gb + supply + housing + sdcard to above 120 USD:
    https://www.sossolutions.nl/raspberry-pi-5-8gb-starter-kit-compleet

    For just a bit more you have a decent mini computer:
    https://www.aliexpress.com/w/wholesale-mini-pc-x86.html

    Inflation?
    Time to end raspi stuff and look for other solutions.


    Arduinos are very cheap and don't have all the overhead the Pi has in
    terms of video capabilities. Plus they're piss-easy to program.
    A Pi 5 plus accessories for 120 bux doesn't sound bad at all, though.
    Or if you're really that much of a skinflint, you could consider PIC >>programming. :-)

    I use this Pi 4 8 GB for web browsing, posting stuff here, spectrum analyzer, radio reception , music play, so much more
    An arduno is something totally different.
    But this 4 8GB is dead slow at times browsing the web.
    Added a metal case with fan now to prevent it from throtling on over-temperature
    so now its hovers around
    temp=40.9'C
    temp=41.3'C
    temp=40.4'
    ..
    Just cut and paste

    Has a 4 TB Toshiba harddisc connected to it, some RTL-SDR stick, A huawei 4G stick so I have internet on it,
    a HDMI monitor, and for all the other USB stuff a Sitecom USB hub, a Logitech wireless keyboard... and that IR FLIR camera on GPIO.

    raspberrypi: ~ # df
    Filesystem 1K-blocks Used Available Use% Mounted on
    /dev/root 30421240 27643352 1432704 96% /
    devtmpfs 3879380 0 3879380 0% /dev
    tmpfs 4044244 0 4044244 0% /dev/shm
    tmpfs 1617700 1336 1616364 1% /run
    tmpfs 5120 4 5116 1% /run/lock
    /dev/mmcblk0p1 258095 50413 207682 20% /boot
    tmpfs 808848 24 808824 1% /run/user/1000
    /dev/sda2 3844420600 2863079020 785980916 79% /mnt/sda2

    raspberrypi: ~ # top
    top - 07:27:40 up 1 day, 22:12, 11 users, load average: 0.64, 0.66, 0.97 >Tasks: 221 total, 1 running, 220 sleeping, 0 stopped, 0 zombie
    %Cpu(s): 4.8 us, 4.3 sy, 0.0 ni, 90.8 id, 0.1 wa, 0.0 hi, 0.1 si, 0.0 st
    MiB Mem : 7898.9 total, 6529.0 free, 727.2 used, 642.7 buff/cache >MiB Swap: 100.0 total, 100.0 free, 0.0 used. 6853.9 avail Mem
    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1105 root 19 -1 195056 77668 56360 S 10.2 1.0 195:49.13 Xorg
    12594 root 20 0 980792 351696 161036 S 6.6 4.3 7:45.00 firefox-esr
    12782 root 20 0 496732 164380 94644 S 3.9 2.0 2:14.18 Web Content
    1123 root 20 0 48028 12892 8604 S 1.6 0.2 0:01.86 rxvt
    1219 root 20 0 6644 4208 3832 S 1.6 0.1 37:20.43 xosview
    12732 root 20 0 640868 135868 81320 S 1.3 1.7 1:02.58 WebExtensions
    ....


    As to PIC programming, how about a simple oscilloscope with FFT option:
    https://panteltje.nl/panteltje/pic/scope_pic/
    from
    https://panteltje.nl/panteltje/pic/index.html
    Or controlling a drone:
    https://panteltje.nl/panteltje/quadcopter/index.html
    From:
    https://panteltje.nl/panteltje/newsflex/download.html

    and now show us somthing YOU designed, code YOU wrote, THAT WORKS!
    And stop meddling here as if you are a censor, Billy blacklisting game with J Lurking
    This is a non-moderated group, bring in some more content than boat anchors and show us!

    !



    No idea what you mean, Jan. I'm 100% against censorship!

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Waldek Hebisch@21:1/5 to Jan Panteltje on Sun Nov 17 01:34:45 2024
    Jan Panteltje <alien@comet.invalid> wrote:

    What bothers me today (thought maybe use an extra Raspberry Pi) is that prices
    are going up to insane lavels for a Raspi5 8 Gb + supply + housing + sdcard to above 120 USD:
    https://www.sossolutions.nl/raspberry-pi-5-8gb-starter-kit-compleet

    For just a bit more you have a decent mini computer:
    https://www.aliexpress.com/w/wholesale-mini-pc-x86.html

    Inflation?
    Time to end raspi stuff and look for other solutions.

    I bought Raspberry Pi 1B when they appeared, but after that used
    Chinese alternatives. Orange Pi used to be cheap, most is more
    expensive now. But Orange Pi Zero 3 is reasonably priced and
    powerful enough for my purpose. You apparently want PC class machine,
    for this I want real PC. For light use mini-PCs may be enough and
    are quite cheap. I got one for equvalent of $70, 6GB RAM, dual core
    Celeron N3350, 64 GB solid state disc, 2 USB 3.0 slots (+ 2 USB 2.0),
    LAN, Wifi, of course in case and with included power supply. For
    me important advantage is that there is no fan (passive cooling only).
    Less powerful used mini-PCs can be as cheap as equivalent of $5.

    Supposedly some "TV boxes" are cheap, resonably powerful and can
    be programmed with Linux. But I did not try one.

    Pi-s are better for electronics/automation thanks to available
    interfaces, but that needs much less compute power (camera is the
    only high bandwidth interface that I use). When you are satified
    with lower compute power there are some cheap ones. I am trying
    now Milkv Duo. Radxa ROCK also seem to be reasonably priced.
    But once you want faster CPU, more RAM, EMMC, etc they are getting
    more expensive. I am not sure why, memory modules for PC seem
    to be cheaper than price of adding memory to SBC-s (possibly this
    is just pure marketing).

    --
    Waldek Hebisch

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Waldek Hebisch on Sun Nov 17 06:36:43 2024
    On a sunny day (Sun, 17 Nov 2024 01:34:45 -0000 (UTC)) it happened antispam@fricas.org (Waldek Hebisch) wrote in <vhbh7j$26abk$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:

    What bothers me today (thought maybe use an extra Raspberry Pi) is that prices
    are going up to insane lavels for a Raspi5 8 Gb + supply + housing + sdcard to above 120 USD:
    https://www.sossolutions.nl/raspberry-pi-5-8gb-starter-kit-compleet

    For just a bit more you have a decent mini computer:
    https://www.aliexpress.com/w/wholesale-mini-pc-x86.html

    Inflation?
    Time to end raspi stuff and look for other solutions.

    I bought Raspberry Pi 1B when they appeared, but after that used
    Chinese alternatives.

    Same here, have some old Pi2 versions...
    one Pi2 is on 24/7 running a server, measuring air pressure, radiation,
    this Pi4 8 GB I use for web browsing and Usenet
    a Pi4 4 GB records security cams and plays audio, records airplane traffic (with dump1090)
    and lots more stuff...

    Orange Pi used to be cheap, most is more
    expensive now. But Orange Pi Zero 3 is reasonably priced and
    powerful enough for my purpose. You apparently want PC class machine,
    for this I want real PC.

    I have several 'real' PCs.. but those are big and use a lot of power, have DVD burner, huge harddisks,
    Almost never on these days, stopped burning optical disks, almost all USB harddisks for data storage now.

    For light use mini-PCs may be enough and
    are quite cheap. I got one for equvalent of $70, 6GB RAM, dual core
    Celeron N3350, 64 GB solid state disc, 2 USB 3.0 slots (+ 2 USB 2.0),
    LAN, Wifi, of course in case and with included power supply. For
    me important advantage is that there is no fan (passive cooling only).
    Less powerful used mini-PCs can be as cheap as equivalent of $5.

    Sound good, x86 based is nice too, have written lotd of stuff for that

    Supposedly some "TV boxes" are cheap, resonably powerful and can
    be programmed with Linux. But I did not try one.

    Indeed, I have several satellite reception boxes, HD recording and playback no problem with those
    some have internet connection too, record to USB SD stick.
    When full with stuff I like to keep I copy it to a 4 TB Toshiba USB harddisk connected to my Pi4 8 GB.

    I do have a satellite reception PCI card in an old x86 PC too, but that is not HD.
    But wrote a lot of software for it.


    Pi-s are better for electronics/automation thanks to available
    interfaces, but that needs much less compute power (camera is the
    only high bandwidth interface that I use).

    Yes, GPIO is nice, on the PCs I uses the parport for I/O,
    even specifically bought a parport PCI card for that on ebay..

    Much goes via ethernet these days and that works fine on Rspberry too.
    Building / designing things with ethernet interface is not that hard.
    severl projects on my site:
    https://panteltje.nl/panteltje/newsflex/download.html
    USB is also fast enough for many things.


    When you are satified
    with lower compute power there are some cheap ones. I am trying
    now Milkv Duo. Radxa ROCK also seem to be reasonably priced.
    But once you want faster CPU, more RAM, EMMC, etc they are getting
    more expensive. I am not sure why, memory modules for PC seem
    to be cheaper than price of adding memory to SBC-s (possibly this
    is just pure marketing).

    Yes, a lot of marketing is involved
    You get sort of addicted to GPIO with Raspberries...
    Anyways how much processing power do I really need?

    I program a lot of stuff in asm for Microchip PICs:
    https://panteltje.nl/panteltje/pic/index.html

    This world creates bloat sftware so it can sell new hardware, Microsoft has shares in hardware companies,
    so new bloat needs new hardware.. more money
    Does it give any new functions?
    Have not noticed really :-)

    Yesterday I was looking for 3D holographics displays, but they have a long way to go there
    Perhaps you could project a rotating fake 3D Christmas tree..
    What they call 3D is not even that..
    Rotating LED strips:
    https://www.bol.com/nl/nl/p/embyance-premium-3d-hologram-projector-hologram-fan-halloween-1024x640-resolutie-holografische-projector-met-app/9300000188728239/

    I did that by hand:
    https://panteltje.nl/panteltje/pic/sign_pic/

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Waldek Hebisch@21:1/5 to Jan Panteltje on Sun Nov 17 14:50:58 2024
    Jan Panteltje <alien@comet.invalid> wrote:
    On a sunny day (Sun, 17 Nov 2024 01:34:45 -0000 (UTC)) it happened antispam@fricas.org (Waldek Hebisch) wrote in <vhbh7j$26abk$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:

    What bothers me today (thought maybe use an extra Raspberry Pi) is that prices
    are going up to insane lavels for a Raspi5 8 Gb + supply + housing + sdcard to above 120 USD:
    https://www.sossolutions.nl/raspberry-pi-5-8gb-starter-kit-compleet

    For just a bit more you have a decent mini computer:
    https://www.aliexpress.com/w/wholesale-mini-pc-x86.html

    Inflation?
    Time to end raspi stuff and look for other solutions.

    I bought Raspberry Pi 1B when they appeared, but after that used
    Chinese alternatives.

    Same here, have some old Pi2 versions...
    one Pi2 is on 24/7 running a server, measuring air pressure, radiation,
    this Pi4 8 GB I use for web browsing and Usenet
    a Pi4 4 GB records security cams and plays audio, records airplane traffic (with dump1090)
    and lots more stuff...

    Orange Pi used to be cheap, most is more
    expensive now. But Orange Pi Zero 3 is reasonably priced and
    powerful enough for my purpose. You apparently want PC class machine,
    for this I want real PC.

    I have several 'real' PCs.. but those are big and use a lot of power, have DVD burner, huge harddisks,
    Almost never on these days, stopped burning optical disks, almost all USB harddisks for data storage now.

    I mostly depend on storing data on multiple HDD-s (my PC have mirrored
    pair of discs and I have extra discs for backup). In last several years
    I did not burn any DVD-s, but maybe I will do some with importand data
    for extra safety (DVD are too small for bulk data).

    I depend on data stored on HDD, most is fetched from Internert but
    things vanish randomly from the net and I have my own indices of
    interesting data, so I normally use local copy from my disk. Also,
    have some compute intensive stuff.

    For light use mini-PCs may be enough and
    are quite cheap. I got one for equvalent of $70, 6GB RAM, dual core >>Celeron N3350, 64 GB solid state disc, 2 USB 3.0 slots (+ 2 USB 2.0),
    LAN, Wifi, of course in case and with included power supply. For
    me important advantage is that there is no fan (passive cooling only).
    Less powerful used mini-PCs can be as cheap as equivalent of $5.

    Sound good, x86 based is nice too, have written lotd of stuff for that

    Supposedly some "TV boxes" are cheap, resonably powerful and can
    be programmed with Linux. But I did not try one.

    Indeed, I have several satellite reception boxes, HD recording and playback no problem with those
    some have internet connection too, record to USB SD stick.
    When full with stuff I like to keep I copy it to a 4 TB Toshiba USB harddisk connected to my Pi4 8 GB.

    I do have a satellite reception PCI card in an old x86 PC too, but that is not HD.
    But wrote a lot of software for it.


    Pi-s are better for electronics/automation thanks to available
    interfaces, but that needs much less compute power (camera is the
    only high bandwidth interface that I use).

    Yes, GPIO is nice, on the PCs I uses the parport for I/O,
    even specifically bought a parport PCI card for that on ebay..

    Much goes via ethernet these days and that works fine on Rspberry too. Building / designing things with ethernet interface is not that hard.
    severl projects on my site:
    https://panteltje.nl/panteltje/newsflex/download.html
    USB is also fast enough for many things.

    USB can do milliseconds, ethernet hundreds of microseconds, small
    micros can do much better. Theoretically with a micro connected via USB
    one can synchronize clocks of the micro and PC with microsecond
    accuracy, I plan to try this but do not know how this will work.

    When you are satified
    with lower compute power there are some cheap ones. I am trying
    now Milkv Duo. Radxa ROCK also seem to be reasonably priced.
    But once you want faster CPU, more RAM, EMMC, etc they are getting
    more expensive. I am not sure why, memory modules for PC seem
    to be cheaper than price of adding memory to SBC-s (possibly this
    is just pure marketing).

    Yes, a lot of marketing is involved
    You get sort of addicted to GPIO with Raspberries...
    Anyways how much processing power do I really need?

    I program a lot of stuff in asm for Microchip PICs:
    https://panteltje.nl/panteltje/pic/index.html

    Nice. I have avoided PICs, using now mostly STM32 and coding in C.
    One can create quite small and efficient programs in C. I use
    assembler when I feel it is better but currently that is mainly
    for delay loop. Doing all in efficient assembler would be large
    effort for moderate gain (maybe 20% efficiency/size improvement),
    and IME "easy assembler" tend to be less efficient than C.

    This world creates bloat sftware so it can sell new hardware, Microsoft has shares in hardware companies,
    so new bloat needs new hardware.. more money

    I dislike bloat but OTOH thanks to bloat powerful PC-s are available
    at affordable price. Otherwise they would be an expensive industry/
    corporate items.

    --
    Waldek Hebisch

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Waldek Hebisch on Sun Nov 17 16:42:27 2024
    On a sunny day (Sun, 17 Nov 2024 14:50:58 -0000 (UTC)) it happened antispam@fricas.org (Waldek Hebisch) wrote in <vhcvsg$28q26$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:
    On a sunny day (Sun, 17 Nov 2024 01:34:45 -0000 (UTC)) it happened
    antispam@fricas.org (Waldek Hebisch) wrote in
    <vhbh7j$26abk$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:

    What bothers me today (thought maybe use an extra Raspberry Pi) is that prices
    are going up to insane lavels for a Raspi5 8 Gb + supply + housing + sdcard to above 120 USD:
    https://www.sossolutions.nl/raspberry-pi-5-8gb-starter-kit-compleet

    For just a bit more you have a decent mini computer:
    https://www.aliexpress.com/w/wholesale-mini-pc-x86.html

    Inflation?
    Time to end raspi stuff and look for other solutions.

    I bought Raspberry Pi 1B when they appeared, but after that used
    Chinese alternatives.

    Same here, have some old Pi2 versions...
    one Pi2 is on 24/7 running a server, measuring air pressure, radiation,
    this Pi4 8 GB I use for web browsing and Usenet
    a Pi4 4 GB records security cams and plays audio, records airplane traffic (with dump1090)
    and lots more stuff...

    Orange Pi used to be cheap, most is more
    expensive now. But Orange Pi Zero 3 is reasonably priced and
    powerful enough for my purpose. You apparently want PC class machine, >>>for this I want real PC.

    I have several 'real' PCs.. but those are big and use a lot of power, have DVD burner, huge harddisks,
    Almost never on these days, stopped burning optical disks, almost all USB harddisks for data storage now.

    I mostly depend on storing data on multiple HDD-s (my PC have mirrored
    pair of discs and I have extra discs for backup). In last several years
    I did not burn any DVD-s, but maybe I will do some with importand data
    for extra safety (DVD are too small for bulk data).

    Blu-ray discs are 25 GB...
    From my dvd-list.txt file for disc 998:
    998
    Tue Oct 8 12:43:07 CEST 2019
    BD-R25GB <---disc type
    Mediarange 4x inkjet printable
    LG BH10LS38 <---burner type
    PLEASE STOP ANY RTL_SDR write data errors observed when that is running! <--- warning!
    Make sure you have enough disk space.
    dd if=/dev/zero bs=100000000 count=242 > bluray.iso
    mke2fs bluray.iso
    mount -o loop=/dev/loop0 bluray.iso /mnt/loop
    cp ... /mnt/loop/
    du /mnt/loop
    #umount /dev/loop0
    umount /mnt/loop
    cd /mnt/sda1/video/satellite
    growisofs -speed=4 -dvd-compat -Z /dev/dvd=bluray.iso
    dvdimagecmp -a bluray.iso -b /dev/dvd
    # df
    /dev/loop0 23261268 21022524 1057104 96% /mnt/loop
    # l/mnt/loop/
    total 20977548
    -rw-r--r-- 1 root root 19095 May 7 23:33 xinutop_manual.txt
    -rw-r--r-- 1 root root 4385000000 Jul 1 18:01 freibeuter_des_todes_german.ts amovie
    -rw-r--r-- 1 root root 58 Jul 11 10:40 xinutop-nav-x86-2.4.img.md5 -rw-r--r-- 1 root root 682624000 Jul 11 10:44 xinutop-nav-x86-2.4.img -rw-r--r-- 1 root root 4294705152 Sep 8 01:51 stones_havana_NPO_3-20190907213907-.mts amovie
    -rw-r--r-- 1 root root 627385344 Sep 8 02:28 stones_havana_NPO_3-20190907213907-.mts1 amovie
    -rw-r--r-- 1 root root 3949971456 Sep 8 05:59 stones_havana_NPO_3-20190907235958-.mts amovie
    -rw-r--r-- 1 root root 1993500000 Sep 24 16:53 the_great_wall_2016.ts amovie
    -rw-r--r-- 1 root root 2354400000 Oct 3 17:05 last_man_standing_1996.ts amovie
    -rw-r--r-- 1 root root 3172370000 Oct 8 12:39 a_cure_for_wellness_2016__german.ts amovie


    all from satellite...
    I wrote dvdimagecmp to verify the burned image..


    I stopped when my 1000 DVD box was full:
    https://panteltje.nl/pub/CD_box_binnenkant_IXIMG_0549.JPG
    that has everything from old CD-RW, blu-ray, to M-DISCs

    M-DISCs are supposed to last a long time:
    https://en.wikipedia.org/wiki/M-DISC
    Stuff I wrote , OS versions I downloaded, music, videos, stuff I designed...
    If you keep the optical media in the dark then it lasts more than 25 years... Each disk has a number, 1 - 1000 in this case, and I have a large text file with the contents of each number.
    Easy to search with a text editor.
    Many discs are special format, some huge with Reiser filesystem.
    I was reading Linus wants to drop Reiserfs..
    I may leave linux and write my own OS, or use some other Unix.
    wrote a Z80 multitasker once long time ago.. Not a big deal.
    Keep the old Linux distros!



    I depend on data stored on HDD, most is fetched from Internert but
    things vanish randomly from the net and I have my own indices of
    interesting data, so I normally use local copy from my disk. Also,
    have some compute intensive stuff.

    For light use mini-PCs may be enough and
    are quite cheap. I got one for equvalent of $70, 6GB RAM, dual core >>>Celeron N3350, 64 GB solid state disc, 2 USB 3.0 slots (+ 2 USB 2.0), >>>LAN, Wifi, of course in case and with included power supply. For
    me important advantage is that there is no fan (passive cooling only). >>>Less powerful used mini-PCs can be as cheap as equivalent of $5.

    Sound good, x86 based is nice too, have written lotd of stuff for that

    Supposedly some "TV boxes" are cheap, resonably powerful and can
    be programmed with Linux. But I did not try one.

    Indeed, I have several satellite reception boxes, HD recording and playback no problem with those
    some have internet connection too, record to USB SD stick.
    When full with stuff I like to keep I copy it to a 4 TB Toshiba USB harddisk connected to my Pi4 8 GB.

    I do have a satellite reception PCI card in an old x86 PC too, but that is not HD.
    But wrote a lot of software for it.


    Pi-s are better for electronics/automation thanks to available >>>interfaces, but that needs much less compute power (camera is the
    only high bandwidth interface that I use).

    Yes, GPIO is nice, on the PCs I uses the parport for I/O,
    even specifically bought a parport PCI card for that on ebay..

    Much goes via ethernet these days and that works fine on Rspberry too.
    Building / designing things with ethernet interface is not that hard.
    severl projects on my site:
    https://panteltje.nl/panteltje/newsflex/download.html
    USB is also fast enough for many things.

    USB can do milliseconds, ethernet hundreds of microseconds, small
    micros can do much better. Theoretically with a micro connected via USB
    one can synchronize clocks of the micro and PC with microsecond
    accuracy, I plan to try this but do not know how this will work.

    When you are satified
    with lower compute power there are some cheap ones. I am trying
    now Milkv Duo. Radxa ROCK also seem to be reasonably priced.
    But once you want faster CPU, more RAM, EMMC, etc they are getting
    more expensive. I am not sure why, memory modules for PC seem
    to be cheaper than price of adding memory to SBC-s (possibly this
    is just pure marketing).

    Yes, a lot of marketing is involved
    You get sort of addicted to GPIO with Raspberries...
    Anyways how much processing power do I really need?

    I program a lot of stuff in asm for Microchip PICs:
    https://panteltje.nl/panteltje/pic/index.html

    Nice. I have avoided PICs, using now mostly STM32 and coding in C.
    One can create quite small and efficient programs in C. I use
    assembler when I feel it is better but currently that is mainly
    for delay loop. Doing all in efficient assembler would be large
    effort for moderate gain (maybe 20% efficiency/size improvement),
    and IME "easy assembler" tend to be less efficient than C.

    In case of small micros like PICs you are so close to the hardware that you will need
    to know how the various registers and stuff work anyways, no space / too much risc to allow for a compiler to change things.
    Then C or some other high level language makes little sense.
    After programming a few PICs you have build up an asm library and things become simple, repeats.
    I use somebody else's integer math library.
    Have not needed floats yet.. not even here in Fourier transform:
    https://panteltje.nl/panteltje/pic/scope_pic/
    And I opensource everything.


    This world creates bloat sftware so it can sell new hardware, Microsoft has shares in hardware companies,
    so new bloat needs new hardware.. more money

    I dislike bloat but OTOH thanks to bloat powerful PC-s are available
    at affordable price. Otherwise they would be an expensive industry/ >corporate items.

    I do get the impression that all that power these days is only needed for the web-browser to show more advertizing...

    Oh I know about AI...

    LOL

    Long ago there was an article in a German magazine by some professor who controlled some toy cars with just a few neurons
    to make those act with specific behaviour.
    That got me interested in neural nets, programmed some of that suff...
    But so much as they do these days? Mostly storage?
    Grab things from the internet?
    Ask AI...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to Hebisch on Sun Nov 17 09:33:54 2024
    On Sun, 17 Nov 2024 14:50:58 -0000 (UTC), antispam@fricas.org (Waldek
    Hebisch) wrote:

    USB can do milliseconds, ethernet hundreds of microseconds, small
    micros can do much better. Theoretically with a micro connected via USB
    one can synchronize clocks of the micro and PC with microsecond
    accuracy, I plan to try this but do not know how this will work.

    We're designing some products around the RP2040, the Pi Pico
    processor.

    Turns out that in some cases, it's easier to bit-bang an SPI interface
    than program an SPI engine. To fine-tune timings in 7 ns increments,
    we can use no-op instructions.

    I wonder what's a safe c-language NOP single-clock operation that no
    compiler is smart enough to optimize out and doesn't add a bunch of
    loads and stores.

    We're experimenting with that sort of timing on an oscilloscope. The
    GCC or whatever code timing tools don't work in this case.

    Something like

    gpio_put(FIRST_GPIO, 1);
    gpio_put(FIRST_GPIO, 0);
    gpio_put(FIRST_GPIO, 1);
    gpio_put(FIRST_GPIO, 0);

    Makes the port pin change every 7 ns. That's astounding. So maybe a
    dummy port bang is my no-op. Just repeat what we just set it to.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Waldek Hebisch@21:1/5 to Jan Panteltje on Sun Nov 17 20:06:46 2024
    Jan Panteltje <alien@comet.invalid> wrote:
    On a sunny day (Sun, 17 Nov 2024 14:50:58 -0000 (UTC)) it happened antispam@fricas.org (Waldek Hebisch) wrote in <vhcvsg$28q26$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:
    On a sunny day (Sun, 17 Nov 2024 01:34:45 -0000 (UTC)) it happened
    antispam@fricas.org (Waldek Hebisch) wrote in
    <vhbh7j$26abk$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:

    Anyways how much processing power do I really need?

    I program a lot of stuff in asm for Microchip PICs:
    https://panteltje.nl/panteltje/pic/index.html

    Nice. I have avoided PICs, using now mostly STM32 and coding in C.
    One can create quite small and efficient programs in C. I use
    assembler when I feel it is better but currently that is mainly
    for delay loop. Doing all in efficient assembler would be large
    effort for moderate gain (maybe 20% efficiency/size improvement),
    and IME "easy assembler" tend to be less efficient than C.

    In case of small micros like PICs you are so close to the hardware that you will need
    to know how the various registers and stuff work anyways, no space / too much risc to allow for a compiler to change things.
    Then C or some other high level language makes little sense.
    After programming a few PICs you have build up an asm library and things become simple, repeats.

    Well, I heard that PICs are hard to program in C. I am not sure how
    small you mean. Smallest micros I have are MSP430 with 256 bytes of
    RAM and 8kB flash (but AFAICS C would work fine also on smaller ones,
    say 64 bytes of RAM and 1kB flash). Cheapest one is STM8 with 1kB RAM
    and 8kB flash. Smallest STM32 I have has 4kB RAM and 16kB flash, that
    is plenty for many programs (actually I run most test programs entiriely
    in RAM, so 4kB code+data). Of course one needs to work with hardware
    registers and understand hardware. Below is my UART receive routine
    (called from an interrupt handler) Actual data reception is very easy,
    first line gets the data from UART. Rest of routine deals with receive
    buffer (cyclic one):

    void
    do_usart1_rx(void)
    {
    uint8_t c = USART1_DR;
    uint8_t head = i_buff.head;
    uint8_t cnt = (head - i_buff.tail)&BUFF_SIZE_MASK;
    /* Drop characters in case of buffer overflow */
    if (cnt != BUFF_SIZE_MASK) {
    i_buff.buff[head] = c;
    head++;
    head &= BUFF_SIZE_MASK;
    i_buff.head = head;
    }
    }

    Compiler generated assembly for STM32F103 (Cortex M3) is below:

    .global do_usart1_rx
    .thumb
    .thumb_func
    .type do_usart1_rx, %function
    do_usart1_rx:
    @ args = 0, pretend = 0, frame = 0
    @ frame_needed = 0, uses_anonymous_args = 0
    @ link register save eliminated.
    ldr r3, .L7
    ldr r0, [r3]
    ldr r3, .L7+4
    uxtb r0, r0
    ldrb r2, [r3] @ zero_extendqisi2
    ldrb r1, [r3, #1] @ zero_extendqisi2
    uxtb r2, r2
    subs r1, r2, r1
    and r1, r1, #15
    cmp r1, #15
    beq .L1
    adds r1, r3, r2
    adds r2, r2, #1
    and r2, r2, #15
    strb r0, [r1, #2]
    strb r2, [r3]
    .L1:
    bx lr
    .L8:
    .align 2
    .L7:
    .word 1073821700
    .word .LANCHOR0
    .size do_usart1_rx, .-do_usart1_rx

    That is 17 executable instructions, 48 bytes of code and AFAICS only
    two zero-extend instructions could be dropped. So one could save
    2 instructions, but the rest is very much forced by how the processor
    works (and by cyclic buffer logic). Compiled code for Cortex M0
    is slightly different. The same C routine should work on STM8
    (UART port address is different but data register should behave
    the same as on STM32) and GD32VF103 (Riscv core but peripherials
    compatible with STM32F103). Cyclic buffer logic could be copied
    and used on different processors, like MSP430 or AVR.

    Test program for UART routines is 1192 bytes code and uses probably
    about 100 bytes of RAM (36 for global data, the rest is stack (I
    made a conservative guess for possible stack use)). That is about
    1.8% of available code space and 0.5% of available RAM. Of the code
    336 bytes is table of interrupt vectors (essentially its presence is
    forced by the hardware). The program includes setting clock to desired frequency, configuration of pins, UART and interrupt controller.

    BTW, the interrupt handler itself is:

    void
    usart1_isr(void)
    {
    uint32_t isr = USART1_SR;
    if (isr&USART_SR_RXNE) {
    do_usart1_rx();
    }
    if (isr&USART_SR_TXE) {
    do_usart1_tx();
    }
    }

    which generates 32 bytes of code.

    I use somebody else's integer math library.

    Cortex M have hardware 32-bit mutiplication and C compiler will
    expand inline most of 64-bit operations. MSP430 and STM8 needs
    support routines.

    Have not needed floats yet.. not even here in Fourier transform:
    https://panteltje.nl/panteltje/pic/scope_pic/
    And I opensource everything.

    --
    Waldek Hebisch

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to sunaecoNoChoppedPork@gmail.com on Sun Nov 17 12:49:08 2024
    On Sun, 17 Nov 2024 18:28:45 +0000, JM
    <sunaecoNoChoppedPork@gmail.com> wrote:

    On Sun, 17 Nov 2024 09:33:54 -0800, john larkin <JL@gct.com> wrote:

    On Sun, 17 Nov 2024 14:50:58 -0000 (UTC), antispam@fricas.org (Waldek >>Hebisch) wrote:

    USB can do milliseconds, ethernet hundreds of microseconds, small
    micros can do much better. Theoretically with a micro connected via USB >>>one can synchronize clocks of the micro and PC with microsecond
    accuracy, I plan to try this but do not know how this will work.

    We're designing some products around the RP2040, the Pi Pico
    processor.

    Turns out that in some cases, it's easier to bit-bang an SPI interface
    than program an SPI engine. To fine-tune timings in 7 ns increments,
    we can use no-op instructions.

    I wonder what's a safe c-language NOP single-clock operation that no >>compiler is smart enough to optimize out and doesn't add a bunch of
    loads and stores.

    We're experimenting with that sort of timing on an oscilloscope. The
    GCC or whatever code timing tools don't work in this case.

    Something like

    gpio_put(FIRST_GPIO, 1);
    gpio_put(FIRST_GPIO, 0);
    gpio_put(FIRST_GPIO, 1);
    gpio_put(FIRST_GPIO, 0);

    Makes the port pin change every 7 ns. That's astounding. So maybe a
    dummy port bang is my no-op. Just repeat what we just set it to.


    Code in assembly. It's trivial to use assembly code with c in gcc.

    A gpio_put to an unused port pin would work, but we don't have any
    unused port pins.

    I suspect that we could clear some internal device register, like in a
    timer or something, that we don't use. That would kill a clock or so
    and the compiler can't know that we don't use it.

    My guy did

    gpio up
    A = 3+5
    gpio down

    and of course the add takes zero time.

    A = A+5

    does take time, looks like four clocks.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Waldek Hebisch on Mon Nov 18 06:47:04 2024
    On a sunny day (Sun, 17 Nov 2024 20:06:46 -0000 (UTC)) it happened antispam@fricas.org (Waldek Hebisch) wrote in <vhdick$29o3r$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:
    On a sunny day (Sun, 17 Nov 2024 14:50:58 -0000 (UTC)) it happened
    antispam@fricas.org (Waldek Hebisch) wrote in
    <vhcvsg$28q26$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:
    On a sunny day (Sun, 17 Nov 2024 01:34:45 -0000 (UTC)) it happened
    antispam@fricas.org (Waldek Hebisch) wrote in
    <vhbh7j$26abk$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:

    Anyways how much processing power do I really need?

    I program a lot of stuff in asm for Microchip PICs:
    https://panteltje.nl/panteltje/pic/index.html

    Nice. I have avoided PICs, using now mostly STM32 and coding in C.
    One can create quite small and efficient programs in C. I use
    assembler when I feel it is better but currently that is mainly
    for delay loop. Doing all in efficient assembler would be large
    effort for moderate gain (maybe 20% efficiency/size improvement),
    and IME "easy assembler" tend to be less efficient than C.

    In case of small micros like PICs you are so close to the hardware that you will need
    to know how the various registers and stuff work anyways, no space / too much risc to allow for a compiler to change things.
    Then C or some other high level language makes little sense.
    After programming a few PICs you have build up an asm library and things become simple, repeats.

    Well, I heard that PICs are hard to program in C. I am not sure how
    small you mean. Smallest micros I have are MSP430 with 256 bytes of
    RAM and 8kB flash (but AFAICS C would work fine also on smaller ones,
    say 64 bytes of RAM and 1kB flash). Cheapest one is STM8 with 1kB RAM
    and 8kB flash. Smallest STM32 I have has 4kB RAM and 16kB flash, that
    is plenty for many programs (actually I run most test programs entiriely
    in RAM, so 4kB code+data). Of course one needs to work with hardware >registers and understand hardware. Below is my UART receive routine
    (called from an interrupt handler) Actual data reception is very easy,
    first line gets the data from UART. Rest of routine deals with receive >buffer (cyclic one):

    void
    do_usart1_rx(void)
    {
    uint8_t c = USART1_DR;
    uint8_t head = i_buff.head;
    uint8_t cnt = (head - i_buff.tail)&BUFF_SIZE_MASK;
    /* Drop characters in case of buffer overflow */
    if (cnt != BUFF_SIZE_MASK) {
    i_buff.buff[head] = c;
    head++;
    head &= BUFF_SIZE_MASK;
    i_buff.head = head;
    }
    }

    Compiler generated assembly for STM32F103 (Cortex M3) is below:

    .global do_usart1_rx
    .thumb
    .thumb_func
    .type do_usart1_rx, %function
    do_usart1_rx:
    @ args = 0, pretend = 0, frame = 0
    @ frame_needed = 0, uses_anonymous_args = 0
    @ link register save eliminated.
    ldr r3, .L7
    ldr r0, [r3]
    ldr r3, .L7+4
    uxtb r0, r0
    ldrb r2, [r3] @ zero_extendqisi2
    ldrb r1, [r3, #1] @ zero_extendqisi2
    uxtb r2, r2
    subs r1, r2, r1
    and r1, r1, #15
    cmp r1, #15
    beq .L1
    adds r1, r3, r2
    adds r2, r2, #1
    and r2, r2, #15
    strb r0, [r1, #2]
    strb r2, [r3]
    .L1:
    bx lr
    .L8:
    .align 2
    .L7:
    .word 1073821700
    .word .LANCHOR0
    .size do_usart1_rx, .-do_usart1_rx

    That is 17 executable instructions, 48 bytes of code and AFAICS only
    two zero-extend instructions could be dropped. So one could save
    2 instructions, but the rest is very much forced by how the processor
    works (and by cyclic buffer logic). Compiled code for Cortex M0
    is slightly different. The same C routine should work on STM8
    (UART port address is different but data register should behave
    the same as on STM32) and GD32VF103 (Riscv core but peripherials
    compatible with STM32F103). Cyclic buffer logic could be copied
    and used on different processors, like MSP430 or AVR.

    Test program for UART routines is 1192 bytes code and uses probably
    about 100 bytes of RAM (36 for global data, the rest is stack (I
    made a conservative guess for possible stack use)). That is about
    1.8% of available code space and 0.5% of available RAM. Of the code
    336 bytes is table of interrupt vectors (essentially its presence is
    forced by the hardware). The program includes setting clock to desired >frequency, configuration of pins, UART and interrupt controller.

    BTW, the interrupt handler itself is:

    void
    usart1_isr(void)
    {
    uint32_t isr = USART1_SR;
    if (isr&USART_SR_RXNE) {
    do_usart1_rx();
    }
    if (isr&USART_SR_TXE) {
    do_usart1_tx();
    }
    }

    which generates 32 bytes of code.

    I use somebody else's integer math library.

    Cortex M have hardware 32-bit mutiplication and C compiler will
    expand inline most of 64-bit operations. MSP430 and STM8 needs
    support routines.

    Have not needed floats yet.. not even here in Fourier transform:
    https://panteltje.nl/panteltje/pic/scope_pic/
    And I opensource everything.

    Yes it all depends, I still have my old 8052 BASIC computer:
    https://panteltje.nl/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_inside2_img_1757.jpg
    wrote an assembler for it so I could do inline assembler in the BASIC.
    I used 5 pole audio connectors to make teh i2c bus external, with sensors and stuff connected to it all around the house.
    from before year 2000.

    As to PIC serial code
    As you can see from the below example, PIC asm is very simple and straight forward.
    That is the code in my GPS based radiation meter / logger with OLED display and SDcard storage:
    https://panteltje.nl/panteltje/pic/gm_pic2/
    Still working 24/7 after all these years... can hear it ticking on rasiation, logs to a Raspberry Pi 4 4 GB via a serial to USB adaptor.
    ASM code:
    https://panteltje.nl/panteltje/pic/gm_pic2/gm_pic2-0.8.asm

    I like to comment in the code, but it is basically very simple.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Waldek Hebisch@21:1/5 to Jan Panteltje on Mon Nov 18 10:38:06 2024
    Jan Panteltje <alien@comet.invalid> wrote:

    Yes it all depends, I still have my old 8052 BASIC computer:
    https://panteltje.nl/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_inside2_img_1757.jpg
    wrote an assembler for it so I could do inline assembler in the BASIC.
    I used 5 pole audio connectors to make teh i2c bus external, with sensors and stuff connected to it all around the house.
    from before year 2000.

    Around 1985 I planned to build a Z80 machine, but then I got ZX Spectrum
    and there was no need to build it.

    As to PIC serial code
    As you can see from the below example, PIC asm is very simple and straight forward.
    That is the code in my GPS based radiation meter / logger with OLED display and SDcard storage:
    https://panteltje.nl/panteltje/pic/gm_pic2/
    Still working 24/7 after all these years... can hear it ticking on rasiation, logs to a Raspberry Pi 4 4 GB via a serial to USB adaptor.
    ASM code:
    https://panteltje.nl/panteltje/pic/gm_pic2/gm_pic2-0.8.asm

    I like to comment in the code, but it is basically very simple.

    Well, I used to think "assembler requires comparable effort to C and
    is more efficient", but then I looked how much time both take
    and compared efficiency: assembler may be more efficient but
    efficient assember requires significantly more effort than C.
    One can write assembler in a way that saves effort, but then
    it tends to be less efficient than output of a good C compiler,
    and still takes a bit more effort than C. You may be used
    to assembler, but if you are used to both, then reading C is
    easier than reading assembler.

    Anyway, I see no reason to use PIC-s, from normal sources
    I would have to pay more for them than I pay for STM32 and
    I see no special advantage of PICs.

    BTW: It seems that there are few thousends of instructions in
    your code, AFAICS object code for such a program when compiled
    for something like STM32 would be of comparable size and C source
    would be smaller.

    --
    Waldek Hebisch

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Waldek Hebisch on Mon Nov 18 11:21:34 2024
    On a sunny day (Mon, 18 Nov 2024 10:38:06 -0000 (UTC)) it happened antispam@fricas.org (Waldek Hebisch) wrote in <vhf5ec$2h6bb$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:

    Yes it all depends, I still have my old 8052 BASIC computer:
    https://panteltje.nl/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_inside2_img_1757.jpg
    wrote an assembler for it so I could do inline assembler in the BASIC.
    I used 5 pole audio connectors to make teh i2c bus external, with sensors and stuff connected to it all around the house.
    from before year 2000.

    Around 1985 I planned to build a Z80 machine, but then I got ZX Spectrum
    and there was no need to build it.

    As to PIC serial code
    As you can see from the below example, PIC asm is very simple and straight forward.
    That is the code in my GPS based radiation meter / logger with OLED display and SDcard storage:
    https://panteltje.nl/panteltje/pic/gm_pic2/
    Still working 24/7 after all these years... can hear it ticking on rasiation, logs to a Raspberry Pi 4 4 GB via a serial to
    USB adaptor.
    ASM code:
    https://panteltje.nl/panteltje/pic/gm_pic2/gm_pic2-0.8.asm

    I like to comment in the code, but it is basically very simple.

    Well, I used to think "assembler requires comparable effort to C and
    is more efficient", but then I looked how much time both take
    and compared efficiency: assembler may be more efficient but
    efficient assember requires significantly more effort than C.
    One can write assembler in a way that saves effort, but then
    it tends to be less efficient than output of a good C compiler,
    and still takes a bit more effort than C. You may be used
    to assembler, but if you are used to both, then reading C is
    easier than reading assembler.

    Anyway, I see no reason to use PIC-s, from normal sources
    I would have to pay more for them than I pay for STM32 and
    I see no special advantage of PICs.

    BTW: It seems that there are few thousends of instructions in
    your code, AFAICS object code for such a program when compiled
    for something like STM32 would be of comparable size and C source
    would be smaller.

    Yep, but most of that is in every 18F14K22 PIC code I wrote or from that
    so all that just an afternoon or 2 to make it work.

    I am not against C, but so close to the hardware as in the example I gave it makes little sense.
    I use C all the time:
    https://panteltje.nl/panteltje/newsflex/download.html
    this Newsrreader I am using to read and reply here is written in C:
    https://panteltje.nl/panteltje/newsflex/index.html
    that uses linked lists,
    I have a database of Usenet postings that goes back to my first Linux use in 1998 or so...
    wrote that newsreader as there was no Free Agent for Linux...
    Also in C is all the raspi code I wrote, no asm there at all,
    but I use many libraries that may contain asm...
    https://panteltje.nl/panteltje/newsflex/download.html
    No C plush plush here... No Python either..
    The problem with using someone else's libraries is that those often change, change maintainer and then lose functionalities or do not work at all anymore.


    Well programming is fun, languages are interesting too, also the ones humans use,
    do speak Dutch, Englitch, German, little bit Spanish, French, Pizza, what not...
    C is nice for floating point math too, for more pointless things asm is fine.
    I like to make fun of languages...
    All code seems to work though..
    Logic Mr Spock, logic.
    Same for hardware, I come from a hardware background, programming came later. Maybe kids these days start with writing code and then learn about chips and perhaps transistors.?
    Like taking a train where a short walk would do.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Waldek Hebisch@21:1/5 to Jan Panteltje on Mon Nov 18 20:56:58 2024
    Jan Panteltje <alien@comet.invalid> wrote:
    On a sunny day (Mon, 18 Nov 2024 10:38:06 -0000 (UTC)) it happened antispam@fricas.org (Waldek Hebisch) wrote in <vhf5ec$2h6bb$1@paganini.bofh.team>:

    Jan Panteltje <alien@comet.invalid> wrote:

    Yes it all depends, I still have my old 8052 BASIC computer:
    https://panteltje.nl/pub/8052AH_BASIC_computer/8052AH_BASIC_computer_inside2_img_1757.jpg
    wrote an assembler for it so I could do inline assembler in the BASIC.
    I used 5 pole audio connectors to make teh i2c bus external, with sensors and stuff connected to it all around the house.
    from before year 2000.

    Around 1985 I planned to build a Z80 machine, but then I got ZX Spectrum >>and there was no need to build it.

    As to PIC serial code
    As you can see from the below example, PIC asm is very simple and straight forward.
    That is the code in my GPS based radiation meter / logger with OLED display and SDcard storage:
    https://panteltje.nl/panteltje/pic/gm_pic2/
    Still working 24/7 after all these years... can hear it ticking on rasiation, logs to a Raspberry Pi 4 4 GB via a serial to
    USB adaptor.
    ASM code:
    https://panteltje.nl/panteltje/pic/gm_pic2/gm_pic2-0.8.asm

    I like to comment in the code, but it is basically very simple.

    Well, I used to think "assembler requires comparable effort to C and
    is more efficient", but then I looked how much time both take
    and compared efficiency: assembler may be more efficient but
    efficient assember requires significantly more effort than C.
    One can write assembler in a way that saves effort, but then
    it tends to be less efficient than output of a good C compiler,
    and still takes a bit more effort than C. You may be used
    to assembler, but if you are used to both, then reading C is
    easier than reading assembler.

    Anyway, I see no reason to use PIC-s, from normal sources
    I would have to pay more for them than I pay for STM32 and
    I see no special advantage of PICs.

    BTW: It seems that there are few thousends of instructions in
    your code, AFAICS object code for such a program when compiled
    for something like STM32 would be of comparable size and C source
    would be smaller.

    Yep, but most of that is in every 18F14K22 PIC code I wrote or from that
    so all that just an afternoon or 2 to make it work.

    I am not against C, but so close to the hardware as in the example I gave it makes little sense.

    "so close to the hardware" does not change much. I have routines
    handling almost all buitin devices in STM32F030, most devices
    in STM32F103 and many devices in other models (STM has resonable
    compatibility between models so a single routine covers a lot
    of models). They directly access device register, configure them
    etc. I do not see how you could get "closer to the hardware".
    Writing them in C was significantly easier than writing them in
    assembler, using them is easier too. Assembler could give me
    some marginal efficiency gains which in most cases do no matter.
    And when extra efficiency really matteres I can rewrite _what is
    needed_ in assembler. For example, I wanted to know how far
    I can push nominally 400kHz I2C periferial in MSP430. Bottleneck
    was in I2C interrupt handler, so I did it in assembler. And the
    answer is: I2C worked reasonably well up to about 1.4MHz and
    almost worked at 2.4MHz (almost worked meant that data went
    back and forth, but was slightly mangled). But for normal use
    at 400kHz interrupt handler in C is fine.

    BTW, the routines I mention are written by me and deliberatly
    are very close to the hardware. When I needed to use things
    unhanlded by my routines (mainly USB and ENC28J60) I used
    C routines that I fetched from the net. ENC28J60 routine
    actually was for AVR, but most of it was idependent of the
    CPU, so I just replaced the critical part and used the
    rest without changes. You can find changes that I made to
    'libmaple' on the Github (however orginal authors do not
    develop it anymore and I also for most things am using
    different code).

    I use C all the time:
    https://panteltje.nl/panteltje/newsflex/download.html
    this Newsrreader I am using to read and reply here is written in C:
    https://panteltje.nl/panteltje/newsflex/index.html
    that uses linked lists,
    I have a database of Usenet postings that goes back to my first Linux use in 1998 or so...
    wrote that newsreader as there was no Free Agent for Linux...
    Also in C is all the raspi code I wrote, no asm there at all,
    but I use many libraries that may contain asm...
    https://panteltje.nl/panteltje/newsflex/download.html
    No C plush plush here... No Python either..
    The problem with using someone else's libraries is that those often change, change maintainer and then lose functionalities or do not work at all anymore.

    Well, I am using libopencm3 from about 2015 (newer version have
    significant incompatibilities). Actually I am phasing out use of it,
    ATM I am using it mainly for definitions of various magic constants.
    I decided to write may own routines which as I wrote are closer to
    the hardware and smaller than routines in libopencm3 (which in turn
    seem to be smaller than routines in STM developement pack).

    So one can use old code or enhance it when mainainers make undesirable
    changes. At some moment I intended to do signioficant developement
    on libmaple, but then decided that the design had significant
    problems, so did my routines in quite a different way.

    --
    Waldek Hebisch

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Waldek Hebisch@21:1/5 to john larkin on Mon Nov 18 21:22:26 2024
    john larkin <JL@gct.com> wrote:
    On Sun, 17 Nov 2024 14:50:58 -0000 (UTC), antispam@fricas.org (Waldek Hebisch) wrote:

    USB can do milliseconds, ethernet hundreds of microseconds, small
    micros can do much better. Theoretically with a micro connected via USB >>one can synchronize clocks of the micro and PC with microsecond
    accuracy, I plan to try this but do not know how this will work.

    We're designing some products around the RP2040, the Pi Pico
    processor.

    Turns out that in some cases, it's easier to bit-bang an SPI interface
    than program an SPI engine. To fine-tune timings in 7 ns increments,
    we can use no-op instructions.

    I wonder what's a safe c-language NOP single-clock operation that no
    compiler is smart enough to optimize out and doesn't add a bunch of
    loads and stores.

    As JM wrote, with gcc (and I think clang too) you can use imline asm
    like:

    __asm__ volatile ("nop");

    gcc is supposed to keep it. There is potential trouble with reordering,
    in general gcc can move statements to a different place when it thinks
    that the affect is the same. 'volatile' is supposed to prevent such
    movement (gcc still may move "normal" code around it, but access to
    GPIO should be volatile too and gcc will not reorder volatile
    operations).

    We're experimenting with that sort of timing on an oscilloscope. The
    GCC or whatever code timing tools don't work in this case.

    Oscilloscope is good to see what happens at the pins. For observing
    internal time one can read systick register (I did not check RP2040,
    but I think it can be configured to change every clock).

    Something like

    gpio_put(FIRST_GPIO, 1);
    gpio_put(FIRST_GPIO, 0);
    gpio_put(FIRST_GPIO, 1);
    gpio_put(FIRST_GPIO, 0);

    Makes the port pin change every 7 ns. That's astounding. So maybe a
    dummy port bang is my no-op. Just repeat what we just set it to.

    I you want accuracy up to a single clock, then your code is brittle.
    RP2040 is a complex device and can do many things simultaneously.
    There is large potential for undesired interference. Basically,
    if you have code in a single bank of the RAM and your RP2040 is
    doing nothing else than bit-banging, then you are resonably safe.
    However, if SPI peripherial can do what you need, then IMO it
    is better solution, as SPI is dedicated hardware block which can
    operate without interference in parallel with other blocks.

    --
    Waldek Hebisch

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Waldek Hebisch@21:1/5 to Edward Rawde on Mon Nov 18 23:49:33 2024
    Edward Rawde <invalid@invalid.invalid> wrote:
    "Jan Panteltje" <alien@comet.invalid> wrote in message news:vgq37s$oo9h$1@solani.org...
    On a sunny day (Sun, 10 Nov 2024 09:51:49 -0000 (UTC)) it happened Cursitor >> Doom <cd999666@notformail.com> wrote in <vgpvnk$ao84$1@dont-email.me>:

    On Sat, 9 Nov 2024 21:40:06 +0000, Liz Tuddenham wrote:

    Cursitor Doom <cd@notformail.com> wrote:

    [...]
    There's not a single person on this group today who can really add any >>>>> value here.

    You do them a dis-service, there are some people here who can think with >>>> an open mind. Even if the ideas they come up with wouldn't work, trying >>>> to find out or explain why they wouldn't work is a good exercise and may >>>> lead to a better solution than just asking hams what they have done
    before.

    OK, that's entirely your call. But I think you'll find the number of >>>people here with expertise in VHF receiver design is zero and the >>>proportion of those with an adequate familiarity with designing for toobz >>>is a vanishingly small subset of that figure. :)


    I designed plenty of VHF rx stuff, teefee works in that range,
    including UHF.
    But to go back in time and do it with toobs? No, I used transistors.
    Only case I could think of for using toobs is when all semi-conductors
    were destroyed by radiation.
    But not much would be on air to listen for in that case.
    And in that case shortwave would be a better place to listen for remaining lifeforms.
    And grounded grid does not make a lot of sense, has not many advantages for a VHF input stage.

    Why?
    https://www.google.com/search?&q=valve+fm+tuner&udm=2
    I can see at least two grounded grids and I don't recall a transistor FM tuner without a grounded base first stage.
    Reduced sensitivity was ofted caused by a need to replace that transistor because being the first stage it gets what the antenna
    gets.

    I have no experience with radio design, but for curiosity looked at
    several early TV sets from soviet block. _All_ tube circuits that
    I found were common cathode in first stage, in late sixties apparently
    they converged on caskode configuration (two early designs had
    two common cathode stages). I found also few early transistor
    circunts, majority was common base, one was common emiter. I
    think reasonable guess is that tube characteristics make caskode
    preferable, while for transitors (at least those from sixties and
    seventies) common base seem to be better.

    --
    Waldek Hebisch

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to Hebisch on Mon Nov 18 16:13:55 2024
    On Mon, 18 Nov 2024 21:22:26 -0000 (UTC), antispam@fricas.org (Waldek
    Hebisch) wrote:

    john larkin <JL@gct.com> wrote:
    On Sun, 17 Nov 2024 14:50:58 -0000 (UTC), antispam@fricas.org (Waldek
    Hebisch) wrote:

    USB can do milliseconds, ethernet hundreds of microseconds, small
    micros can do much better. Theoretically with a micro connected via USB >>>one can synchronize clocks of the micro and PC with microsecond
    accuracy, I plan to try this but do not know how this will work.

    We're designing some products around the RP2040, the Pi Pico
    processor.

    Turns out that in some cases, it's easier to bit-bang an SPI interface
    than program an SPI engine. To fine-tune timings in 7 ns increments,
    we can use no-op instructions.

    I wonder what's a safe c-language NOP single-clock operation that no
    compiler is smart enough to optimize out and doesn't add a bunch of
    loads and stores.

    As JM wrote, with gcc (and I think clang too) you can use imline asm
    like:

    __asm__ volatile ("nop");

    gcc is supposed to keep it. There is potential trouble with reordering,
    in general gcc can move statements to a different place when it thinks
    that the affect is the same. 'volatile' is supposed to prevent such
    movement (gcc still may move "normal" code around it, but access to
    GPIO should be volatile too and gcc will not reorder volatile
    operations).

    We're experimenting with that sort of timing on an oscilloscope. The
    GCC or whatever code timing tools don't work in this case.

    Oscilloscope is good to see what happens at the pins. For observing
    internal time one can read systick register (I did not check RP2040,
    but I think it can be configured to change every clock).

    Something like

    gpio_put(FIRST_GPIO, 1);
    gpio_put(FIRST_GPIO, 0);
    gpio_put(FIRST_GPIO, 1);
    gpio_put(FIRST_GPIO, 0);

    Makes the port pin change every 7 ns. That's astounding. So maybe a
    dummy port bang is my no-op. Just repeat what we just set it to.

    I you want accuracy up to a single clock, then your code is brittle.
    RP2040 is a complex device and can do many things simultaneously.
    There is large potential for undesired interference. Basically,
    if you have code in a single bank of the RAM and your RP2040 is
    doing nothing else than bit-banging, then you are resonably safe.
    However, if SPI peripherial can do what you need, then IMO it
    is better solution, as SPI is dedicated hardware block which can
    operate without interference in parallel with other blocks.

    The CPUs are Alice and Bob. Alice is the manager, doing USB and
    Ethernet and blinking LEDs and stuff. It will run code out of the big
    serial flash, cached.

    Bob is the realtime bare-metal processor. It will run one main loop
    and get one periodic interrupt at 120 KHz. It will bit-bang the SPI
    interface of the dreadful AD7699 8-channel ADC. Bob will run out of
    ram so should be perfectly repeatable.

    We figure that the IRQ can read one ADC channel, and run for about 2
    usec, which leaves 3/4 of Bob's compute power for the main loop.

    Do not read the ADC data sheet unless you have good medical insurance
    that includes PTSD coverage.

    The RP2040 does an instruction in 7 ns. I recall when Cray stunned the
    world with a big ECL liquid-freon-cooled computer with a 7 ns clock.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jan Panteltje@21:1/5 to Waldek Hebisch on Tue Nov 19 06:56:15 2024
    On a sunny day (Mon, 18 Nov 2024 23:49:33 -0000 (UTC)) it happened antispam@fricas.org (Waldek Hebisch) wrote in <vhgjqb$2jj9t$1@paganini.bofh.team>:

    I have no experience with radio design, but for curiosity looked at
    several early TV sets from soviet block. _All_ tube circuits that
    I found were common cathode in first stage, in late sixties apparently
    they converged on caskode configuration (two early designs had
    two common cathode stages). I found also few early transistor
    circunts, majority was common base, one was common emiter. I
    think reasonable guess is that tube characteristics make caskode
    preferable, while for transitors (at least those from sixties and
    seventies) common base seem to be better.

    Moved to satellite years ago, for very high frequencies GHz with tranistors all common emitter.
    LNB example figure 5 for input stage:
    https://www.nxp.com/docs/en/application-note/AN11698.pdf

    A similar Chinese LNB inside:
    https://panteltje.nl/pub/5_dollar_LNB_PCB_IMG_3582.GIF

    That one has a ceramic oscillator,
    there are ones with crystal oscillors,
    https://panteltje.nl/pub/octagon_twin_LNB_OTLSO_inside_RT320M_PLL_IMG_6538.JPG have modified one for external crystal oscialliator locked to a Rubidium reference..
    frequency stability required for SSB on satellite...
    https://panteltje.nl/pub/ethernet_controlled_LNB_reference_cicuit_diagram_IMG_6848.JPG

    Those LNBs are really very low noise.
    There is more to it ...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)