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
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
On 08/06/2024 22:47, John R Walliker wrote:
On 08/06/2024 20:43, john larkin wrote:Most of the connectors in the image look like SMB which is a "click on"
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
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
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: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
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
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.
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:
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.
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: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
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
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.
On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doom <cd999666@notformail.com> wrote:rlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1
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:Most of the connectors in the image look like SMB which is a "click
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
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?
That pin is around 100 ohms in free space!rlkey=1eonuljqekvrszyb9tce5s1hr&raw=1
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?
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:Most of the connectors in the image look like SMB which is a "click >>>>>on"
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
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. ;-)
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:Most of the connectors in the image look like SMB which is a "click >>>>>>on"
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
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.
On Sun, 09 Jun 2024 08:03:18 -0700, john larkin wrote:
On Sun, 9 Jun 2024 10:19:52 -0000 (UTC), Cursitor Doomrlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1
<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:Most of the connectors in the image look like SMB which is a "click
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
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=1eonuljqekvrszyb9tce5s1hr&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?
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. ;-)
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 Doomrlkey=nbmbyb0f54uslcpc0nh7rs21p&raw=1
<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:Most of the connectors in the image look like SMB which is a "click >>>>>> on"
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
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=1eonuljqekvrszyb9tce5s1hr&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?
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.
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
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
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
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:Most of the connectors in the image look like SMB which is a "click >>>>>>>on"
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
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.
Cursitor Doom <cd999666@notformail.com> wrote:
Gentlemen,U.FL.
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
Cheers
Phil Hobbs
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