• RF Connector Type ID

    From Cursitor Doom@21:1/5 to All on Sat Jun 8 18:10:59 2024
    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for interconnecting the boards of their analyzers to route 50 ohm RF signals
    around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Edward Rawde@21:1/5 to Cursitor Doom on Sat Jun 8 14:41:23 2024
    "Cursitor Doom" <cd999666@notformail.com> wrote in message news:v426ri$2ni84$1@dont-email.me...
    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for interconnecting the boards of their analyzers to route 50 ohm RF signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Some variant of sma?
    https://www.google.com/search?q=sma+connector

    smb and smc also exist.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to cd999666@notformail.com on Sat Jun 8 12:43:13 2024
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for >interconnecting the boards of their analyzers to route 50 ohm RF signals >around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to jrwalliker@gmail.com on Sat Jun 8 17:06:18 2024
    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for
    interconnecting the boards of their analyzers to route 50 ohm RF signals >>>> around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click on"
    push fit connector and is cylindrical at the end. A few which have a
    hex profile at the end may be SMC which is a threaded connector.
    SMA is threaded and a bit larger, but has the best high frequency
    performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without tools,
    so can be mounted very close together. They work fine to 6 or 8 GHz,
    about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper pad
    stack keeps things 50 ohms.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to john larkin on Sun Jun 9 10:19:52 2024
    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for
    interconnecting the boards of their analyzers to route 50 ohm RF
    signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click on" >>push fit connector and is cylindrical at the end. A few which have a
    hex profile at the end may be SMC which is a threaded connector.
    SMA is threaded and a bit larger, but has the best high frequency >>performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without tools,
    so can be mounted very close together. They work fine to 6 or 8 GHz,
    about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper pad
    stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never
    encountered a 'pad stack' before.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Bill Sloman@21:1/5 to Cursitor Doom on Sun Jun 9 23:15:44 2024
    On 9/06/2024 8:19 pm, Cursitor Doom wrote:
    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    <snip>

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper pad
    stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never encountered a 'pad stack' before.

    You need to manage the transition between 50R transmission line in the
    cable and the 50R trace in the board. Traces buried in the board can be non-dispersive, and you can work out how wide the trace has to be and
    how far from ground planes that carry the return current to get you 50R.

    A connector on the edge of the board needs special care. The pad stack
    is a collection of metalised areas in the edge of the board that provide
    a more-or-less seamless transition.

    --
    Bill Sloman, Sydney


    --
    This email has been checked for viruses by Norton antivirus software. www.norton.com

    --- SoupGate-Win32 v1.05
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  • From john larkin@21:1/5 to cd999666@notformail.com on Sun Jun 9 08:03:18 2024
    On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:

    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for
    interconnecting the boards of their analyzers to route 50 ohm RF
    signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click on" >>>push fit connector and is cylindrical at the end. A few which have a
    hex profile at the end may be SMC which is a threaded connector.
    SMA is threaded and a bit larger, but has the best high frequency >>>performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without tools,
    so can be mounted very close together. They work fine to 6 or 8 GHz,
    about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper pad
    stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never >encountered a 'pad stack' before.

    A PCB's pad stack is a diagram of the number of conductive and
    insulating layers and their thickesses and composition. It must be
    specified when you buy a board.

    Sometimes you get to choose between a few canned stacks, and sometimes
    you diagram your own.

    We mostly do 4 and 6-layer boards, with some 2-layer and the
    occasional 8 or even 10 copper layers. Never single layer.

    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane
    is too close to the center pin of the connector, so that bit of the
    signal path is too low impedance. So one does creative shaped cutouts
    in the various layers to keep the impedance uniform and the
    reflections down. We did e-m simulations (with ATLC) and test boards
    to get that right.

    The cheaper connectors have a giant round center pin, which requires
    attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG?rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG?rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to john larkin on Sun Jun 9 16:41:15 2024
    On Sun, 09 Jun 2024 08:03:18 -0700, john larkin wrote:

    On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:

    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for >>>>>>> interconnecting the boards of their analyzers to route 50 ohm RF >>>>>>> signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click
    on"
    push fit connector and is cylindrical at the end. A few which have a >>>>hex profile at the end may be SMC which is a threaded connector.
    SMA is threaded and a bit larger, but has the best high frequency >>>>performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without tools,
    so can be mounted very close together. They work fine to 6 or 8 GHz,
    about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper pad
    stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never >>encountered a 'pad stack' before.

    A PCB's pad stack is a diagram of the number of conductive and
    insulating layers and their thickesses and composition. It must be
    specified when you buy a board.

    Sometimes you get to choose between a few canned stacks, and sometimes
    you diagram your own.

    We mostly do 4 and 6-layer boards, with some 2-layer and the occasional
    8 or even 10 copper layers. Never single layer.

    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane is
    too close to the center pin of the connector, so that bit of the signal
    path is too low impedance. So one does creative shaped cutouts in the
    various layers to keep the impedance uniform and the reflections down.
    We did e-m simulations (with ATLC) and test boards to get that right.

    The cheaper connectors have a giant round center pin, which requires attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG?
    rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG?
    rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    Thanks, John; I'm somewhat less ignorant now than I was!
    Seriously though, it's clear the reason I've not encountered these is due
    to the fact I just experiment with single layer boards which don't need
    them, from what you implicitly state. Life must get really "interesting"
    with RF in multi-layer boards. ;-)

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to cd999666@notformail.com on Sun Jun 9 10:25:32 2024
    On Sun, 9 Jun 2024 16:41:15 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:

    On Sun, 09 Jun 2024 08:03:18 -0700, john larkin wrote:

    On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for >>>>>>>> interconnecting the boards of their analyzers to route 50 ohm RF >>>>>>>> signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click >>>>>on"
    push fit connector and is cylindrical at the end. A few which have a >>>>>hex profile at the end may be SMC which is a threaded connector.
    SMA is threaded and a bit larger, but has the best high frequency >>>>>performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without tools, >>>> so can be mounted very close together. They work fine to 6 or 8 GHz,
    about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper pad
    stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never >>>encountered a 'pad stack' before.

    A PCB's pad stack is a diagram of the number of conductive and
    insulating layers and their thickesses and composition. It must be
    specified when you buy a board.

    Sometimes you get to choose between a few canned stacks, and sometimes
    you diagram your own.

    We mostly do 4 and 6-layer boards, with some 2-layer and the occasional
    8 or even 10 copper layers. Never single layer.

    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an
    edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane is
    too close to the center pin of the connector, so that bit of the signal
    path is too low impedance. So one does creative shaped cutouts in the
    various layers to keep the impedance uniform and the reflections down.
    We did e-m simulations (with ATLC) and test boards to get that right.

    The cheaper connectors have a giant round center pin, which requires
    attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG? >rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG? >rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    Thanks, John; I'm somewhat less ignorant now than I was!
    Seriously though, it's clear the reason I've not encountered these is due
    to the fact I just experiment with single layer boards which don't need
    them, from what you implicitly state. Life must get really "interesting"
    with RF in multi-layer boards. ;-)

    We do picosecond time-domain stuff, which resembles RF except that is broadband, all the way down to DC, so we can't tweak to tune things
    into some narrow RF band.

    I expect that it's impossible to do really fast stuff, 30 GHz-ish,
    with parts soldered to FR4 PC boards.

    I just disassembled a National Instruments PXIe RF module (with great difficulty) and it's really bizarre. And it's only 6 GHz!

    I might post some pics.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Cursitor Doom@21:1/5 to john larkin on Sun Jun 9 17:31:54 2024
    On Sun, 09 Jun 2024 10:25:32 -0700, john larkin wrote:

    On Sun, 9 Jun 2024 16:41:15 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:

    On Sun, 09 Jun 2024 08:03:18 -0700, john larkin wrote:

    On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot >>>>>>>>> for interconnecting the boards of their analyzers to route 50 >>>>>>>>> ohm RF signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click >>>>>>on"
    push fit connector and is cylindrical at the end. A few which have >>>>>>a hex profile at the end may be SMC which is a threaded connector. >>>>>>SMA is threaded and a bit larger, but has the best high frequency >>>>>>performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without
    tools,
    so can be mounted very close together. They work fine to 6 or 8 GHz, >>>>> about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper
    pad stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never >>>>encountered a 'pad stack' before.

    A PCB's pad stack is a diagram of the number of conductive and
    insulating layers and their thickesses and composition. It must be
    specified when you buy a board.

    Sometimes you get to choose between a few canned stacks, and sometimes
    you diagram your own.

    We mostly do 4 and 6-layer boards, with some 2-layer and the
    occasional 8 or even 10 copper layers. Never single layer.

    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an
    edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane
    is too close to the center pin of the connector, so that bit of the
    signal path is too low impedance. So one does creative shaped cutouts
    in the various layers to keep the impedance uniform and the
    reflections down. We did e-m simulations (with ATLC) and test boards
    to get that right.

    The cheaper connectors have a giant round center pin, which requires
    attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG? >>rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG? >>rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    Thanks, John; I'm somewhat less ignorant now than I was!
    Seriously though, it's clear the reason I've not encountered these is
    due to the fact I just experiment with single layer boards which don't
    need them, from what you implicitly state. Life must get really >>"interesting" with RF in multi-layer boards. ;-)

    We do picosecond time-domain stuff, which resembles RF except that is broadband, all the way down to DC, so we can't tweak to tune things into
    some narrow RF band.

    I expect that it's impossible to do really fast stuff, 30 GHz-ish, with
    parts soldered to FR4 PC boards.

    I just disassembled a National Instruments PXIe RF module (with great difficulty) and it's really bizarre. And it's only 6 GHz!

    I might post some pics.

    Please do! I struggle with parasitics at even modest frequencies so it's
    always fascinating to see how the pros overcome these barriers.

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to Cursitor Doom on Sun Jun 9 19:42:19 2024
    On 6/9/24 18:41, Cursitor Doom wrote:
    On Sun, 09 Jun 2024 08:03:18 -0700, john larkin wrote:

    On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for >>>>>>>> interconnecting the boards of their analyzers to route 50 ohm RF >>>>>>>> signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click
    on"
    push fit connector and is cylindrical at the end. A few which have a >>>>> hex profile at the end may be SMC which is a threaded connector.
    SMA is threaded and a bit larger, but has the best high frequency
    performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without tools, >>>> so can be mounted very close together. They work fine to 6 or 8 GHz,
    about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper pad
    stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never
    encountered a 'pad stack' before.

    A PCB's pad stack is a diagram of the number of conductive and
    insulating layers and their thickesses and composition. It must be
    specified when you buy a board.

    Sometimes you get to choose between a few canned stacks, and sometimes
    you diagram your own.

    We mostly do 4 and 6-layer boards, with some 2-layer and the occasional
    8 or even 10 copper layers. Never single layer.

    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an
    edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane is
    too close to the center pin of the connector, so that bit of the signal
    path is too low impedance. So one does creative shaped cutouts in the
    various layers to keep the impedance uniform and the reflections down.
    We did e-m simulations (with ATLC) and test boards to get that right.

    The cheaper connectors have a giant round center pin, which requires
    attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG?
    rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG?
    rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    Thanks, John; I'm somewhat less ignorant now than I was!
    Seriously though, it's clear the reason I've not encountered these is due
    to the fact I just experiment with single layer boards which don't need
    them, from what you implicitly state. Life must get really "interesting"
    with RF in multi-layer boards. ;-)

    RF gets more understandable when you realize that electrical
    signals really propagate as electromagnetic fields *between*
    conductors, rather than as currents and voltages.

    Jeroen Belleman

    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From Jeroen Belleman@21:1/5 to john larkin on Sun Jun 9 19:42:52 2024
    On 6/9/24 19:25, john larkin wrote:
    On Sun, 9 Jun 2024 16:41:15 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:

    On Sun, 09 Jun 2024 08:03:18 -0700, john larkin wrote:

    On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot for >>>>>>>>> interconnecting the boards of their analyzers to route 50 ohm RF >>>>>>>>> signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click >>>>>> on"
    push fit connector and is cylindrical at the end. A few which have a >>>>>> hex profile at the end may be SMC which is a threaded connector.
    SMA is threaded and a bit larger, but has the best high frequency
    performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without tools, >>>>> so can be mounted very close together. They work fine to 6 or 8 GHz, >>>>> about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper pad >>>>> stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never
    encountered a 'pad stack' before.

    A PCB's pad stack is a diagram of the number of conductive and
    insulating layers and their thickesses and composition. It must be
    specified when you buy a board.

    Sometimes you get to choose between a few canned stacks, and sometimes
    you diagram your own.

    We mostly do 4 and 6-layer boards, with some 2-layer and the occasional
    8 or even 10 copper layers. Never single layer.

    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an
    edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane is >>> too close to the center pin of the connector, so that bit of the signal
    path is too low impedance. So one does creative shaped cutouts in the
    various layers to keep the impedance uniform and the reflections down.
    We did e-m simulations (with ATLC) and test boards to get that right.

    The cheaper connectors have a giant round center pin, which requires
    attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG?
    rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG?
    rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    Thanks, John; I'm somewhat less ignorant now than I was!
    Seriously though, it's clear the reason I've not encountered these is due
    to the fact I just experiment with single layer boards which don't need
    them, from what you implicitly state. Life must get really "interesting"
    with RF in multi-layer boards. ;-)

    We do picosecond time-domain stuff, which resembles RF except that is broadband, all the way down to DC, so we can't tweak to tune things
    into some narrow RF band.

    I expect that it's impossible to do really fast stuff, 30 GHz-ish,
    with parts soldered to FR4 PC boards.

    I just disassembled a National Instruments PXIe RF module (with great difficulty) and it's really bizarre. And it's only 6 GHz!

    I might post some pics.


    Yes please!

    Jeroen Belleman

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  • From Cursitor Doom@21:1/5 to All on Sun Jun 9 17:26:23 2024
    Gentlemen,

    The previous one I queried was indeed an SMB; many thanks to those who correctly identified it.
    Now, does anyone know anything about these ones? Ignore the N-type part of
    it, I'm referring to the rest of the item in the photo. They too are 50
    ohm and snap-on; very much like SMB but much smaller.
    Any insight would be most welcome.

    https://disk.yandex.com/i/8ZJgAkD-ps5sQQ

    --- SoupGate-Win32 v1.05
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  • From Phil Hobbs@21:1/5 to Cursitor Doom on Sun Jun 9 18:16:41 2024
    Cursitor Doom <cd999666@notformail.com> wrote:
    Gentlemen,

    The previous one I queried was indeed an SMB; many thanks to those who correctly identified it.
    Now, does anyone know anything about these ones? Ignore the N-type part of it, I'm referring to the rest of the item in the photo. They too are 50
    ohm and snap-on; very much like SMB but much smaller.
    Any insight would be most welcome.

    https://disk.yandex.com/i/8ZJgAkD-ps5sQQ



    U.FL.

    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
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  • From Gerhard Hoffmann@21:1/5 to All on Sun Jun 9 22:38:50 2024
    Am 09.06.24 um 17:03 schrieb john larkin:


    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane
    is too close to the center pin of the connector, so that bit of the
    signal path is too low impedance. So one does creative shaped cutouts
    in the various layers to keep the impedance uniform and the
    reflections down. We did e-m simulations (with ATLC) and test boards
    to get that right.

    The cheaper connectors have a giant round center pin, which requires attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG?rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG?rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    That giant center pad gives away the advantage that you could have
    from the costly SMA connector.

    <
    https://www.flickr.com/photos/137684711@N07/51843174578/in/datetaken/ >

    This is nearly as bad as the unpopulated SMA at the right end of the
    line. The left SMA is one with a thick center pin. Unsuitable on this
    cheap JLCPCB 4 layer board. you even see the amount of solder.

    This is the next try: (4 TI LM2594/95 synthesizers + test stuctures)
    <
    https://www.flickr.com/photos/137684711@N07/51844498620/in/datetaken/ >
    red = top, green = bottom, inner layers cut out.

    setup on tdr refl. + transmission:
    <
    https://www.flickr.com/photos/137684711@N07/53780177186/in/dateposted-public/
    >

    result:
    <
    https://www.flickr.com/photos/137684711@N07/53780597885/in/dateposted-public/
    >

    The SMAs are at division 7 and 8. Very slightly overcompensated,
    it could also mean that I need some more GND vias.

    The microstrip is slightly more than 50 Ohms. JLCPCB's calculator
    says 11.5 mil for 50, it took only 10 to see if I can easily escape
    a BGA. The funny bends are not really punished.

    The 10 cm of FR4 do not demolish the rise time. Not bad for
    €1.40 per 4 layer board.

    regards,
    Gerhard

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  • From john larkin@21:1/5 to All on Sun Jun 9 13:51:36 2024
    On Sun, 9 Jun 2024 22:38:50 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
    wrote:

    Am 09.06.24 um 17:03 schrieb john larkin:


    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an
    edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane
    is too close to the center pin of the connector, so that bit of the
    signal path is too low impedance. So one does creative shaped cutouts
    in the various layers to keep the impedance uniform and the
    reflections down. We did e-m simulations (with ATLC) and test boards
    to get that right.

    The cheaper connectors have a giant round center pin, which requires
    attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG?rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG?rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    That giant center pad gives away the advantage that you could have
    from the costly SMA connector.

    That pic was the connector on a PCB that was intended for the big-pin
    part. A skinny trace would be appropriate for the Mueller SMA, but in
    real life the cheaper big-pin part TDRs about the same.


    <
    https://www.flickr.com/photos/137684711@N07/51843174578/in/datetaken/ >

    This is nearly as bad as the unpopulated SMA at the right end of the
    line. The left SMA is one with a thick center pin. Unsuitable on this
    cheap JLCPCB 4 layer board. you even see the amount of solder.

    We tweak the pad stack to compensate for the big pad. That works
    pretty well.


    This is the next try: (4 TI LM2594/95 synthesizers + test stuctures)
    <
    https://www.flickr.com/photos/137684711@N07/51844498620/in/datetaken/ > >red = top, green = bottom, inner layers cut out.

    setup on tdr refl. + transmission:
    < >https://www.flickr.com/photos/137684711@N07/53780177186/in/dateposted-public/
    >

    result:
    < >https://www.flickr.com/photos/137684711@N07/53780597885/in/dateposted-public/

    Big improvement.

    >

    The SMAs are at division 7 and 8. Very slightly overcompensated,
    it could also mean that I need some more GND vias.

    The microstrip is slightly more than 50 Ohms. JLCPCB's calculator
    says 11.5 mil for 50, it took only 10 to see if I can easily escape
    a BGA. The funny bends are not really punished.

    The 10 cm of FR4 do not demolish the rise time. Not bad for
    €1.40 per 4 layer board.

    Short traces on cheap boards are pretty good.


    regards,
    Gerhard





    --- SoupGate-Win32 v1.05
    * Origin: fsxNet Usenet Gateway (21:1/5)
  • From john larkin@21:1/5 to cd999666@notformail.com on Sun Jun 9 14:01:58 2024
    On Sun, 9 Jun 2024 17:31:54 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:

    On Sun, 09 Jun 2024 10:25:32 -0700, john larkin wrote:

    On Sun, 9 Jun 2024 16:41:15 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    On Sun, 09 Jun 2024 08:03:18 -0700, john larkin wrote:

    On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    On Sat, 08 Jun 2024 17:06:18 -0700, john larkin wrote:

    On Sat, 8 Jun 2024 22:54:07 +0100, John R Walliker
    <jrwalliker@gmail.com> wrote:

    On 08/06/2024 22:47, John R Walliker wrote:
    On 08/06/2024 20:43, john larkin wrote:
    On Sat, 8 Jun 2024 18:10:59 -0000 (UTC), Cursitor Doom
    <cd999666@notformail.com> wrote:

    Gentlemen,

    Can anyone identify these connectors? HP use 'em an awful lot >>>>>>>>>> for interconnecting the boards of their analyzers to route 50 >>>>>>>>>> ohm RF signals around the various inside sections.

    Thanks,

    CD.

    https://disk.yandex.com/i/LQ1ytGUQCf7OTw

    Probably SMBs.

    +1

    John

    Most of the connectors in the image look like SMB which is a "click >>>>>>>on"
    push fit connector and is cylindrical at the end. A few which have >>>>>>>a hex profile at the end may be SMC which is a threaded connector. >>>>>>>SMA is threaded and a bit larger, but has the best high frequency >>>>>>>performance of them all.

    John

    We like SMBs because that are quick to mate and un-mate without
    tools,
    so can be mounted very close together. They work fine to 6 or 8 GHz, >>>>>> about what you can do with discretes on FR4.

    Shining Star makes nice cheap edge-launch SMAs and SMBs. A proper
    pad stack keeps things 50 ohms.

    Could you possibly expand on that last sentence, please? I've never >>>>>encountered a 'pad stack' before.

    A PCB's pad stack is a diagram of the number of conductive and
    insulating layers and their thickesses and composition. It must be
    specified when you buy a board.

    Sometimes you get to choose between a few canned stacks, and sometimes >>>> you diagram your own.

    We mostly do 4 and 6-layer boards, with some 2-layer and the
    occasional 8 or even 10 copper layers. Never single layer.

    Our boards are mostly 0.062" thick, and I like layer 2 to be a solid
    ground plane. Some internal layers are power planes. If you solder an
    edge-launch SMA or SMB connector to layer 1, the layer 2 ground plane
    is too close to the center pin of the connector, so that bit of the
    signal path is too low impedance. So one does creative shaped cutouts
    in the various layers to keep the impedance uniform and the
    reflections down. We did e-m simulations (with ATLC) and test boards
    to get that right.

    The cheaper connectors have a giant round center pin, which requires
    attention.

    https://www.dropbox.com/scl/fi/vfi56wy5hkwva51bx77z6/SS_SMA_Edge.JPG? >>>rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1

    That pin is around 100 ohms in free space!

    There are more expensive conectors with a tiny flat pin that
    theoretically matches a layer 1 trace width directly, but I haven't
    found them to be worth it on FR4 boards and 30 ps edges.

    https://www.dropbox.com/scl/fi/rptmh5f4umscqqpegatw6/Mueller_SMA.JPG? >>>rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1

    Thanks, John; I'm somewhat less ignorant now than I was!
    Seriously though, it's clear the reason I've not encountered these is
    due to the fact I just experiment with single layer boards which don't >>>need them, from what you implicitly state. Life must get really >>>"interesting" with RF in multi-layer boards. ;-)

    We do picosecond time-domain stuff, which resembles RF except that is
    broadband, all the way down to DC, so we can't tweak to tune things into
    some narrow RF band.

    I expect that it's impossible to do really fast stuff, 30 GHz-ish, with
    parts soldered to FR4 PC boards.

    I just disassembled a National Instruments PXIe RF module (with great
    difficulty) and it's really bizarre. And it's only 6 GHz!

    I might post some pics.

    Please do! I struggle with parasitics at even modest frequencies so it's >always fascinating to see how the pros overcome these barriers.

    Here it is:

    https://www.dropbox.com/scl/fo/xalh98wfmk5b1m8renaj1/ALK2Mu87IZDBbBtyfa4Sid4?rlkey=u6ymtjdgzp9gl9pkwfw8754p3&dl=0

    The RF PCBs feel like ceramic to me. The top layer whitish stuff is
    conductive.

    As noted, this is bizarre. And obviously very expensive to build.
    What's with those machined cover plates?

    But cheap on ebay! Maybe nobody wants this.

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  • From Cursitor Doom@21:1/5 to Phil Hobbs on Sun Jun 9 23:15:00 2024
    On Sun, 9 Jun 2024 18:16:41 -0000 (UTC), Phil Hobbs wrote:

    Cursitor Doom <cd999666@notformail.com> wrote:
    Gentlemen,

    The previous one I queried was indeed an SMB; many thanks to those who
    correctly identified it.
    Now, does anyone know anything about these ones? Ignore the N-type part
    of it, I'm referring to the rest of the item in the photo. They too are
    50 ohm and snap-on; very much like SMB but much smaller.
    Any insight would be most welcome.

    https://disk.yandex.com/i/8ZJgAkD-ps5sQQ



    U.FL.

    Cheers

    Phil Hobbs

    Aha! Thanks, Phil.

    --- SoupGate-Win32 v1.05
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