• Dressing RG6

    From Don Y@21:1/5 to All on Tue May 14 09:51:38 2024
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Don Y on Tue May 14 17:18:49 2024
    Don Y <blockedofcourse@foo.invalid> wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    You’re planning to make a random- length shotgun balun.

    Cheers

    Phil Hobbs

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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Phil Hobbs on Tue May 14 18:27:08 2024
    Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
    Don Y <blockedofcourse@foo.invalid> wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    You’re planning to make a random- length shotgun balun.

    Cheers

    Phil Hobbs


    Bazooka balun.

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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don@21:1/5 to Phil Hobbs on Tue May 14 19:22:12 2024
    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    You’re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can
    open a Pandora's box of potential problems.

    Danke,

    --
    Don, KB7RPU, https://www.qsl.net/kb7rpu
    There was a young lady named Bright Whose speed was far faster than light;
    She set out one day In a relative way And returned on the previous night.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to Don on Tue May 14 13:13:32 2024
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    You’re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can
    open a Pandora's box of potential problems.

    Danke,

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Tue May 14 21:46:35 2024
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    YouÂ’re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can
    open a Pandora's box of potential problems.

    Danke,

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.



    If the whole system is really coaxial, that’s true. Leaky shields, ground loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    Cheers

    Phil Hobbs

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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Phil Hobbs on Wed May 15 00:08:26 2024
    On 5/14/24 23:46, Phil Hobbs wrote:
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    YouÂ’re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can
    open a Pandora's box of potential problems.

    Danke,

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.



    If the whole system is really coaxial, that’s true. Leaky shields, ground loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    Cheers

    Phil Hobbs


    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don@21:1/5 to John Larkin on Tue May 14 22:20:56 2024
    John Larkin wrote:
    Don wrote:
    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?

    You?re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can
    open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.

    Does a ferrite bead by any other name (eg metal armor) contain parasitic capacitance?

    ... A ferrite bead can be modeled as a simplified circuit
    consisting of resistors, an inductor, and a capacitor ...

    <https://www.analog.com/en/resources/analog-dialogue/articles/ferrite-beads-demystified.html>

    Danke,

    --
    Don, KB7RPU, https://www.qsl.net/kb7rpu
    There was a young lady named Bright Whose speed was far faster than light;
    She set out one day In a relative way And returned on the previous night.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Jeroen Belleman on Tue May 14 23:49:45 2024
    Jeroen Belleman <jeroen@nospam.please> wrote:
    On 5/14/24 23:46, Phil Hobbs wrote:
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    YouÂ’re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can >>>> open a Pandora's box of potential problems.

    Danke,

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.



    If the whole system is really coaxial, that’s true. Leaky shields, ground >> loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    Cheers

    Phil Hobbs


    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Jeroen Belleman

    Interesting, thanks.

    Is that better than real solid copper hardline or (my fave) RG402 semi-hardline?

    I’d like to read more about it, if you have a reference handy.

    Cheers

    Phil Hobbs

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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don@21:1/5 to Jeroen Belleman on Tue May 14 23:33:35 2024
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal armor can >>>> open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, ground >> loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky shields, ground >> loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1]
    the copper tubes or braids?

    Note.

    [1] Whitlock cynicism can be ignored:

    Q. What does "ground" mean?
    A. A fantasy invented by engineers to simplify their work.

    _An Overview of Audio System Grounding & Interfacing_
    by Bill Whitlock

    Danke,

    --
    Don, KB7RPU, https://www.qsl.net/kb7rpu
    There was a young lady named Bright Whose speed was far faster than light;
    She set out one day In a relative way And returned on the previous night.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to Don on Tue May 14 17:31:17 2024
    On Tue, 14 May 2024 23:33:35 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal armor can >>>>> open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1]
    the copper tubes or braids?

    Note.

    [1] Whitlock cynicism can be ignored:

    Q. What does "ground" mean?
    A. A fantasy invented by engineers to simplify their work.

    _An Overview of Audio System Grounding & Interfacing_
    by Bill Whitlock

    Danke,

    I means just what it says. Dirt.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue May 14 17:29:47 2024
    On Tue, 14 May 2024 21:46:35 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    You?re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can
    open a Pandora's box of potential problems.

    Danke,

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.



    If the whole system is really coaxial, that’s true. Leaky shields, ground >loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    Cheers

    Phil Hobbs

    Why can't he just use tie-wraps? Or hot-melt?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Wed May 15 01:52:34 2024
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 21:46:35 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    You?re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can >>>> open a Pandora's box of potential problems.

    Danke,

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.



    If the whole system is really coaxial, thatÂ’s true. Leaky shields, ground >> loops, and so on, will modify that.

    Depending on the application, you may or may not care.


    Why can't he just use tie-wraps? Or hot-melt?



    What a simplistic suggestion!

    This is the Yuniskis world we’re talking about, where nothing is ever so simple as it might seem.

    You might as well suggest that Baer get a new computer!

    (And in my world, RG-58 cables talk to each other all the time.)

    Cheers

    Phil Hobbs



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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Jeroen Belleman on Tue May 14 19:51:38 2024
    On 5/14/2024 3:08 PM, Jeroen Belleman wrote:
    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    But you likely weren't ALSO relying on the tubing for it's
    mechanical characteristics?

    I see no real electrical issues -- a copper pipe is just
    a third (for RG6U) or fifth (for RG6'q') shield layer.
    But, its (desired!) inflexibility adds other complications
    to its deployment.

    - it inherently eliminates any "service loop" so the
    endpoints are fixed, spatially, wrt each other.
    So, positioning those points then becomes important
    along with its constraints on their disconnection!
    (imagine having two or more such connections between
    "end devices", potentially orthogonal to each other!)
    - it transfers any mechanical stresses encountered
    along its length to the supporting endpoints which
    likely weren't designed with that sort of "mechanical
    load" in mind (you're supposed to have a CABLE connected
    there, not some "cantilevered mass"). A passerby
    bumping it anywhere along its length poses a risk.
    - it makes on-site manufacture (by "semi-trained
    installers) more difficult -- e.g., fabricating the
    cable *inside* the tubing (few folks are proficient in
    handling EMT and *that* has much less constraints;
    how much does the inner cable "shrink" with each bend?)

    I assume your deployment was "one-off", done by someone
    skilled in the practice (or, at least able to evaluate
    the quality of their FINISHED work) and likely isolated
    from other "traffic"? You likely wouldn't expect some
    "jamoke" to be able to install it correctly? (dealing with
    the consumer market is a whole different set of challenges)

    It's also been suggested that "tubing" may not be rigid
    enough for my needs -- any impacts might deform it and
    leave lasting stresses on the connections. I will buy some
    type K (the thickest wall tubing commonly available, here)
    and see how much abuse it can take.

    I've been directed to explore plastic solutions as
    an alternative. And, technologies that would allow
    some of the critical dimensions to be avoided in
    their (on-site) manufacture. Sadly, ENT isn't (?)
    available in such small diameters... Maybe PVC??

    Or, sell "assemblies" which means having to settle on
    a small number of configurations and expecting the
    market to adapt to them. :<

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to pcdhSpamMeSenseless@electrooptical. on Tue May 14 20:51:09 2024
    On Wed, 15 May 2024 01:52:34 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 21:46:35 -0000 (UTC), Phil Hobbs
    <pcdhSpamMeSenseless@electrooptical.net> wrote:

    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional >>>>>>>> tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    You?re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can >>>>> open a Pandora's box of potential problems.

    Danke,

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.



    If the whole system is really coaxial, that?s true. Leaky shields, ground >>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.


    Why can't he just use tie-wraps? Or hot-melt?



    What a simplistic suggestion!

    Thank you.

    The more one engineers something, the simpler it should get.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Don on Wed May 15 11:03:22 2024
    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal armor can >>>>> open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1]
    the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Phil Hobbs on Wed May 15 11:07:04 2024
    On 5/15/24 01:49, Phil Hobbs wrote:
    Jeroen Belleman <jeroen@nospam.please> wrote:
    On 5/14/24 23:46, Phil Hobbs wrote:
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional >>>>>>>> tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?



    YouÂ’re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can >>>>> open a Pandora's box of potential problems.

    Danke,

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.



    If the whole system is really coaxial, that’s true. Leaky shields, ground >>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    Cheers

    Phil Hobbs


    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Jeroen Belleman

    Interesting, thanks.

    Is that better than real solid copper hardline or (my fave) RG402 semi-hardline?

    I’d like to read more about it, if you have a reference handy.

    I did some comparative tests. The results are here: <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
    There are a few references too.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Clive Arthur@21:1/5 to Don Y on Wed May 15 16:05:00 2024
    On 14/05/2024 17:51, Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional
    tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?

    How about semi-rigid adhesive lined heat shrink tubing?

    https://www.farnell.com/datasheets/3758112.pdf

    --
    Cheers
    Clive

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to jeroen@nospam.please on Wed May 15 07:27:07 2024
    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal armor can >>>>>> open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, ground >>>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky shields, ground >>>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1]
    the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From John Larkin@21:1/5 to jjSNIPlarkin@highNONOlandtechnology on Wed May 15 08:06:03 2024
    On Wed, 15 May 2024 07:27:07 -0700, John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:

    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal armor can >>>>>>> open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>> shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, ground >>>>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky shields, ground >>>>> loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1]
    the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Just say your data below.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don Y@21:1/5 to Clive Arthur on Wed May 15 09:22:47 2024
    On 5/15/2024 8:05 AM, Clive Arthur wrote:
    On 14/05/2024 17:51, Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    How about semi-rigid adhesive lined heat shrink tubing?

    https://www.farnell.com/datasheets/3758112.pdf

    I'd have to look at it but can't imagine it would be any
    stiffer than RG6 itself.

    Part of the problem IS that stiffness; you can't impose a
    particular shape on the cable that it will keep without
    some other "enforcement". E.g., if you were to directly mate
    to a wall-mounted F-connector, you'd want to quickly bring
    the cable back towards the wall (to keep it from interfering
    with the other items using that "space"). You will, eventually,
    get back to the wall about 6 inches from that connection
    point (2" minimum bend radius; do the geometry).

    Now, you can connect to a splitter -- which can be fastened
    to that same wall (or, a coplanar surface). A few inches later,
    each output from the splitter will now have to find its way to
    its respective destination, avoiding any other devices that
    it encounters on that route and assuming an economical path
    to that destination.

    Then, the *second* wall-mounted F-connector can similarly
    snake around the cabling and devices for the first to
    find *its* devices. Noting, of course, that each such
    device somehow has to get its power and make its network
    connection (i.e., more boxes and cables in the way).

    Canvassing friends and neighbors, it seems that cable TV,
    satellite TV and OTA broadcasts are delivered to the home
    this way. In various combinations depending on the occupant's
    preferences and usage patterns.

    E.g., one of my neighbors has "cable" for his internet connection,
    OTA (roof-mounted antenna) for local TV (and radio!) and satellite
    for his "foreign" TV. Another neighbor has satellite and cable
    for his "domestic" TV (sports junkies) and internet.

    In a two-person household, it seems like 3 tuners are a minimum.
    This assumes two people watching (different programs) and one
    being recorded.

    [Here, SWMBO often ties up two tuners recording concurrent
    programs while I opt to watch a third "live"]

    In a four-person household (i.e., kids), add another 2 or 3
    tuners. Recall that, even if the same program is being watched
    by two occupants ON DIFFERENT TVs, each will want to be able
    to channel-surf without interfering with the other's viewing.

    Five (or more) tuners (cable or OTA) currently require at least
    two physical devices. And, don't forget the cable modem! (I
    assume satellite receivers can be similarly configured).

    A TV tuner (cable or OTA) won't give you any "radio" capabilities
    so add devices for that.

    So, figure 7 (2+2 different types of TV, 2 radio, 1 modem) physical
    devices have to be wired to some number of F-connectors protruding
    from the wall. (and powered and accessed electronically)

    And, you want to put this pile of kit someplace out of the way,
    yet accessible. Professional in appearance. And, maintainable
    (not a hodge-podge of /ad hoc/ wiring). Instead of having an STB
    at *each* TV, a separate HiFi "somewhere", a modem sitting in your
    living room BEHIND that TV, etc.

    So, someplace like a closet, pantry, basement, attic, garage, etc.
    None of which were likely intended to house those bits of kit. Many
    basements are "unfinished", have sparse power distribution, etc.
    All (?) closets are devoid of power -- often true of pantries
    and cupboards, as well. Garages are often not "living spaces"
    (so, are subject to temperature extremes). I.e., houses aren't
    designed with "equipment rooms" in mind (industrial and commercial
    deployments are a piece of cake, by comparison!). So, you are
    intruding on OTHER uses for that space.

    Empirically, it seems like you need a bit less than a square foot
    of "surface" for each device and it's cabling -- IF you can dress
    all of the cabling nice and tight. (and, assuming you are a
    conscientious "installer"!)

    [Remember, YOU don't manufacture any of these devices so have
    to adapt to the mechanical configurations of THEIR manufacturers!]

    And, this is just the run-of-the-mill devices that you're already
    using...

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to John Larkin on Wed May 15 23:25:21 2024
    On 5/15/24 16:27, John Larkin wrote:
    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal armor can >>>>>>> open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>> shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1]
    the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Ah sorry, this message didn't seem to get sent...

    At low frequency, the transfer ratio was simply the ratio
    of screen resistance over characteristic impedance. At medium
    frequencies, a few octaves roughly around 1MHz, there was a dip,
    and above that a steady rise of about 10dB/decade.

    Not all cables behaved the same. RG58 is poorly screened and
    doesn't have the dip. UT141 had a very deep dip.

    Details at
    <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to John Larkin on Wed May 15 23:24:28 2024
    On 5/15/24 17:06, John Larkin wrote:
    On Wed, 15 May 2024 07:27:07 -0700, John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:

    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal armor can >>>>>>>> open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>> shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1]
    the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Just say your data below.


    I didn't?

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Jeroen Belleman on Thu May 16 11:41:19 2024
    On 2024-05-15 17:25, Jeroen Belleman wrote:
    On 5/15/24 16:27, John Larkin wrote:
    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal
    armor can
    open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>> shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, >>>>>> ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky shields, >>>>>> ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1]
    the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Ah sorry, this message didn't seem to get sent...

    At low frequency, the transfer ratio was simply the ratio
    of screen resistance over characteristic impedance. At medium
    frequencies, a few octaves roughly around 1MHz, there was a dip,
    and above that a steady rise of about 10dB/decade.

    Not all cables behaved the same. RG58 is poorly screened and
    doesn't have the dip. UT141 had a very deep dip.

    Details at
    <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.

    Jeroen Belleman

    Very interesting results, Jeroen. Thanks for posting them.

    Is the MF resonance due to the inductive and capacitive coupling
    cancelling each other? (They're 180 degrees out of phase, of course.)

    The frequency is way too low to be a transmission line effect in a 1-m
    length.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC / Hobbs ElectroOptics
    Optics, Electro-optics, Photonics, Analog Electronics
    Briarcliff Manor NY 10510

    http://electrooptical.net
    http://hobbs-eo.com

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Don@21:1/5 to Jeroen Belleman on Fri May 17 03:40:17 2024
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:
    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:
    I've several short (a few feet) lengths of RG6 that I
    would like to "strongly coerce" into assuming a particular
    dressing.

    Securing the cables to a stationary surface isn't practical
    without significantly lengthening them and distorting
    their "natural" routing.

    But, ISTM that I should be able to slip each cable into
    a comparable diameter copper (?) pipe and then use traditional >>>>>>>>> tools to bend that pipe into the appropriate configuration.
    I'd have to observe constraints like minimum bend radius
    but are there other issues that I might "discover" down the
    road?

    You?re planning to make a random- length shotgun balun.

    Bazooka balun.

    The parasitic capacitance created between coax and its metal armor can >>>>>> open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax
    shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Interesting, thanks.

    Is that better than real solid copper hardline or (my fave) RG402
    semi-hardline?

    I’d like to read more about it, if you have a reference handy.

    I did some comparative tests. The results are here: <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.
    There are a few references too.

    To summarize:

    Apparently Jeroen uses CK50 sheathed in copper tubing while his
    colleague's cable is CKB50. The transfer impedance of all tested coax
    cables converge at about 54 MHz - a cable channel's common lower
    frequency range.

    Don Y's primary takeaway from this thread may be to solder both ends
    of his conformal copper to the coax screen underneath.

    Danke,

    --
    Don, KB7RPU, https://www.qsl.net/kb7rpu
    There was a young lady named Bright Whose speed was far faster than light;
    She set out one day In a relative way And returned on the previous night.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Phil Hobbs on Sat May 18 14:19:49 2024
    On 5/16/24 17:41, Phil Hobbs wrote:
    On 2024-05-15 17:25, Jeroen Belleman wrote:
    On 5/15/24 16:27, John Larkin wrote:
    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal >>>>>>>>> armor can
    open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>> shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky
    shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky
    shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1] >>>>> the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Ah sorry, this message didn't seem to get sent...

    At low frequency, the transfer ratio was simply the ratio
    of screen resistance over characteristic impedance. At medium
    frequencies, a few octaves roughly around 1MHz, there was a dip,
    and above that a steady rise of about 10dB/decade.

    Not all cables behaved the same. RG58 is poorly screened and
    doesn't have the dip. UT141 had a very deep dip.

    Details at
    <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.

    Jeroen Belleman

    Very interesting results, Jeroen.  Thanks for posting them.

    Is the MF resonance due to the inductive and capacitive coupling
    cancelling each other?  (They're 180 degrees out of phase, of course.)

    The frequency is way too low to be a transmission line effect in a 1-m length.

    Cheers

    Phil Hobbs


    The original data came from an HP3577 and I recorded only the
    magnitude. Since this looks like a resonance, that's also what
    I'd expect.

    I can't easily go back and look again. I did this in 2009, and
    I'm now retired. At the time, I was trying to make a choice for
    cables connecting beam trajectory pick-ups in the CERN PSB to
    their pre-amplifiers.

    I suppose -but did not verify- that the dip is a resonance of
    the outer inductance with a parasitic capacitance of my setup,
    with the screen resistance as the damping element. I can't quite
    make it fit that model though. The screen resistance doesn't
    differ enough between, for example, UT141 and RG58 to explain a
    deep resonance for the former, and its total absence for the
    latter.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Bill Sloman@21:1/5 to Jeroen Belleman on Sat May 18 23:52:40 2024
    On 15/05/2024 8:08 am, Jeroen Belleman wrote:
    On 5/14/24 23:46, Phil Hobbs wrote:
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Tue, 14 May 2024 19:22:12 -0000 (UTC), "Don" <g@crcomp.net> wrote:

    Phil Hobbs wrote:
    Phil Hobbs wrote:
    Don Y wrote:

    <snip>

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically
    has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    RG402 and RG405 semirigid coaxial cable has been around for ages.

    https://www.awcwire.com/rg-catalog/rg402-coax-cable

    With SMA soldered-on connectors it is good to 22GHz, and a solid copper
    tube as as a outer screen is pretty effective. Some people do have a
    passion for re-inventing the wheel.

    --
    Bill Sloman, Sydney

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to Jeroen Belleman on Sat May 18 15:17:22 2024
    Jeroen Belleman <jeroen@nospam.please> wrote:
    On 5/16/24 17:41, Phil Hobbs wrote:
    On 2024-05-15 17:25, Jeroen Belleman wrote:
    On 5/15/24 16:27, John Larkin wrote:
    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal >>>>>>>>>> armor can
    open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>>> shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky
    shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky
    shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure
    and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically >>>>>>> has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1] >>>>>> the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Ah sorry, this message didn't seem to get sent...

    At low frequency, the transfer ratio was simply the ratio
    of screen resistance over characteristic impedance. At medium
    frequencies, a few octaves roughly around 1MHz, there was a dip,
    and above that a steady rise of about 10dB/decade.

    Not all cables behaved the same. RG58 is poorly screened and
    doesn't have the dip. UT141 had a very deep dip.

    Details at
    <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.

    Jeroen Belleman

    Very interesting results, Jeroen.  Thanks for posting them.

    Is the MF resonance due to the inductive and capacitive coupling
    cancelling each other?  (They're 180 degrees out of phase, of course.)

    The frequency is way too low to be a transmission line effect in a 1-m
    length.

    Cheers

    Phil Hobbs


    The original data came from an HP3577 and I recorded only the
    magnitude. Since this looks like a resonance, that's also what
    I'd expect.

    I can't easily go back and look again. I did this in 2009, and
    I'm now retired. At the time, I was trying to make a choice for
    cables connecting beam trajectory pick-ups in the CERN PSB to
    their pre-amplifiers.

    I suppose -but did not verify- that the dip is a resonance of
    the outer inductance with a parasitic capacitance of my setup,
    with the screen resistance as the damping element. I can't quite
    make it fit that model though. The screen resistance doesn't
    differ enough between, for example, UT141 and RG58 to explain a
    deep resonance for the former, and its total absence for the
    latter.

    Jeroen Belleman


    Plus you had some pretty frou-frou RG58 there, with foil and two braids.

    The normal stuff is one tinned-copper braid with about 80% coverage. You
    can probably make a directional coupler with a pair of patch cords and some heat shrink. (I should try that.)

    Cheers

    Phil Hobbs



    --
    Dr Philip C D Hobbs Principal Consultant ElectroOptical 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 pcdhSpamMeSenseless@electrooptical. on Sat May 18 09:00:09 2024
    On Sat, 18 May 2024 15:17:22 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Jeroen Belleman <jeroen@nospam.please> wrote:
    On 5/16/24 17:41, Phil Hobbs wrote:
    On 2024-05-15 17:25, Jeroen Belleman wrote:
    On 5/15/24 16:27, John Larkin wrote:
    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal >>>>>>>>>>> armor can
    open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>>>> shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky
    shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky
    shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure >>>>>>>> and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically >>>>>>>> has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1] >>>>>>> the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Ah sorry, this message didn't seem to get sent...

    At low frequency, the transfer ratio was simply the ratio
    of screen resistance over characteristic impedance. At medium
    frequencies, a few octaves roughly around 1MHz, there was a dip,
    and above that a steady rise of about 10dB/decade.

    Not all cables behaved the same. RG58 is poorly screened and
    doesn't have the dip. UT141 had a very deep dip.

    Details at
    <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.

    Jeroen Belleman

    Very interesting results, Jeroen.  Thanks for posting them.

    Is the MF resonance due to the inductive and capacitive coupling
    cancelling each other?  (They're 180 degrees out of phase, of course.)

    The frequency is way too low to be a transmission line effect in a 1-m
    length.

    Cheers

    Phil Hobbs


    The original data came from an HP3577 and I recorded only the
    magnitude. Since this looks like a resonance, that's also what
    I'd expect.

    I can't easily go back and look again. I did this in 2009, and
    I'm now retired. At the time, I was trying to make a choice for
    cables connecting beam trajectory pick-ups in the CERN PSB to
    their pre-amplifiers.

    I suppose -but did not verify- that the dip is a resonance of
    the outer inductance with a parasitic capacitance of my setup,
    with the screen resistance as the damping element. I can't quite
    make it fit that model though. The screen resistance doesn't
    differ enough between, for example, UT141 and RG58 to explain a
    deep resonance for the former, and its total absence for the
    latter.

    Jeroen Belleman


    Plus you had some pretty frou-frou RG58 there, with foil and two braids.

    The normal stuff is one tinned-copper braid with about 80% coverage. You
    can probably make a directional coupler with a pair of patch cords and some >heat shrink. (I should try that.)

    Cheers

    Phil Hobbs

    A practical question is what might the coupling be between two close,
    parallel coaxes.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Phil Hobbs@21:1/5 to John Larkin on Sat May 18 18:16:48 2024
    John Larkin <jjSNIPlarkin@highNONOlandtechnology.com> wrote:
    On Sat, 18 May 2024 15:17:22 -0000 (UTC), Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:

    Jeroen Belleman <jeroen@nospam.please> wrote:
    On 5/16/24 17:41, Phil Hobbs wrote:
    On 2024-05-15 17:25, Jeroen Belleman wrote:
    On 5/15/24 16:27, John Larkin wrote:
    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal >>>>>>>>>>>> armor can
    open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>>>>> shouldn't have any external field.

    If the whole system is really coaxial, thatÂ’s true. Leaky >>>>>>>>>> shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, thatÂ’s true. Leaky >>>>>>>>>> shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure >>>>>>>>> and/or reduce the transfer impedance (leakage). I did that to >>>>>>>>> measure small signals in a particle accelerator, which typically >>>>>>>>> has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1] >>>>>>>> the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Ah sorry, this message didn't seem to get sent...

    At low frequency, the transfer ratio was simply the ratio
    of screen resistance over characteristic impedance. At medium
    frequencies, a few octaves roughly around 1MHz, there was a dip,
    and above that a steady rise of about 10dB/decade.

    Not all cables behaved the same. RG58 is poorly screened and
    doesn't have the dip. UT141 had a very deep dip.

    Details at
    <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.

    Jeroen Belleman

    Very interesting results, Jeroen.  Thanks for posting them.

    Is the MF resonance due to the inductive and capacitive coupling
    cancelling each other?  (They're 180 degrees out of phase, of course.) >>>>
    The frequency is way too low to be a transmission line effect in a 1-m >>>> length.

    Cheers

    Phil Hobbs


    The original data came from an HP3577 and I recorded only the
    magnitude. Since this looks like a resonance, that's also what
    I'd expect.

    I can't easily go back and look again. I did this in 2009, and
    I'm now retired. At the time, I was trying to make a choice for
    cables connecting beam trajectory pick-ups in the CERN PSB to
    their pre-amplifiers.

    I suppose -but did not verify- that the dip is a resonance of
    the outer inductance with a parasitic capacitance of my setup,
    with the screen resistance as the damping element. I can't quite
    make it fit that model though. The screen resistance doesn't
    differ enough between, for example, UT141 and RG58 to explain a
    deep resonance for the former, and its total absence for the
    latter.

    Jeroen Belleman


    Plus you had some pretty frou-frou RG58 there, with foil and two braids.

    The normal stuff is one tinned-copper braid with about 80% coverage. You
    can probably make a directional coupler with a pair of patch cords and some >> heat shrink. (I should try that.)


    A practical question is what might the coupling be between two close, parallel coaxes.





    Since I now have a 3-GHz VNA, I might have a try measuring that. The
    coupled amplitude goes like a cosine, so it’s easy to calculate how much interaction length you need for 100% coupling from just one measurement.

    Cheers

    Phil Hobbs

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

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Phil Hobbs on Sat May 18 22:49:32 2024
    On 5/18/24 17:17, Phil Hobbs wrote:
    Jeroen Belleman <jeroen@nospam.please> wrote:
    On 5/16/24 17:41, Phil Hobbs wrote:
    On 2024-05-15 17:25, Jeroen Belleman wrote:
    On 5/15/24 16:27, John Larkin wrote:
    On Wed, 15 May 2024 11:03:22 +0200, Jeroen Belleman
    <jeroen@nospam.please> wrote:

    On 5/15/24 01:33, Don wrote:
    Jeroen Belleman wrote:
    Phil Hobbs wrote:
    John Larkin wrote:
    Don wrote:

    <snip>

    The parasitic capacitance created between coax and its metal >>>>>>>>>>> armor can
    open a Pandora's box of potential problems.

    Capacitance between the coax outer and the copper pipe? Proper coax >>>>>>>>>> shouldn't have any external field.

    If the whole system is really coaxial, that’s true. Leaky
    shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.
    If the whole system is really coaxial, that’s true. Leaky
    shields, ground
    loops, and so on, will modify that.

    Depending on the application, you may or may not care.

    I've been putting coax inside copper tubes or braids to measure >>>>>>>> and/or reduce the transfer impedance (leakage). I did that to
    measure small signals in a particle accelerator, which typically >>>>>>>> has kicker magnets and RF cavities with kA currents and kV
    voltages nearby.

    A colleague developed a special low transfer impedance coax
    cable for this sort of application. It had two screens with
    intermediate magnetic shielding. It was unpleasant to work
    with, because part of the magnetic shielding was a steel
    spiral foil tape that was razor sharp. But it worked really
    well.

    Empirical observation always trumps theory for me. Did you ground [1] >>>>>>> the copper tubes or braids?

    Both ends were connected to the connector shields. The point of
    the exercise was to reduce transfer impedance, which at low
    frequency (<1MHz) is simply proportional to screen resistance.

    Jeroen Belleman

    Two parallel coaxes can make an attenuator.

    What was the coupled frequency response like?

    Ah sorry, this message didn't seem to get sent...

    At low frequency, the transfer ratio was simply the ratio
    of screen resistance over characteristic impedance. At medium
    frequencies, a few octaves roughly around 1MHz, there was a dip,
    and above that a steady rise of about 10dB/decade.

    Not all cables behaved the same. RG58 is poorly screened and
    doesn't have the dip. UT141 had a very deep dip.

    Details at
    <https://jeroen.web.cern.ch/jeroen/coaxleakage/leakage.shtml>.

    Jeroen Belleman

    Very interesting results, Jeroen.  Thanks for posting them.

    Is the MF resonance due to the inductive and capacitive coupling
    cancelling each other?  (They're 180 degrees out of phase, of course.)

    The frequency is way too low to be a transmission line effect in a 1-m
    length.

    Cheers

    Phil Hobbs


    The original data came from an HP3577 and I recorded only the
    magnitude. Since this looks like a resonance, that's also what
    I'd expect.

    I can't easily go back and look again. I did this in 2009, and
    I'm now retired. At the time, I was trying to make a choice for
    cables connecting beam trajectory pick-ups in the CERN PSB to
    their pre-amplifiers.

    I suppose -but did not verify- that the dip is a resonance of
    the outer inductance with a parasitic capacitance of my setup,
    with the screen resistance as the damping element. I can't quite
    make it fit that model though. The screen resistance doesn't
    differ enough between, for example, UT141 and RG58 to explain a
    deep resonance for the former, and its total absence for the
    latter.

    Jeroen Belleman


    Plus you had some pretty frou-frou RG58 there, with foil and two braids.

    The normal stuff is one tinned-copper braid with about 80% coverage. You
    can probably make a directional coupler with a pair of patch cords and some heat shrink. (I should try that.)

    Cheers

    Phil Hobbs

    This was Draka's version of RG58, I think it was made to CERN's
    specs, fire retardant and rad-hard. From an RF standpoint, it
    wasn't so fancy and it didn't fit very well in standard RG58-
    compatible connectors.

    Speaking of directional couplers, I made one with bits of UT85.
    It was inspired by a 1979 publication by Udo Barabas in IEEE
    Transactions on Microwave Theory and Techniques. It worked
    surprisingly well, with a measured transmission bandwidth of
    40kHz to 9GHz, although the directivity deteriorated beyond a
    GHz or so. It was a rough demo of the concept. I'm sure it's
    possible to do much better. It was my suggestion for a GHz
    bandwidth beam position signal processing front-end in the
    LHC.

    I wrote it up in <https://jeroen.web.cern.ch/jeroen/Barabas/>.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)