Hi all,
I'm seeking about this kind of PCB test jack described (page5 Fig.11) in this document :
I would be very grateful if someone could point me where i can purchase them.
Best Regards, Habib.
We often use SMB connectors with series resistors to the circuit nodes to be probed.
The cluster of 9 SMB footprints is for probing PCI Express.
This assumes a 50 ohm cable and scope input. Bandwidth is many GHz.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Those were made by Tektronix. You might try Qservice in Rhodes, Gr. These are HP's version:
Also, here are some:
tm
Thank you but i'll manage with John Larkin suggestion. We may need many of these PCB tests connectors (several hundred) and long term support.
Best Regards, H.
No problem. John knows what he is doing.
Although SMB are less convenient because of more insertion effort i will nevertheless proceed to PCB launch.
Best Regards.
SMBs are relatively cheap. Unlke SMAs, or those scope probe things, you can put them close together.
MCXs would be good, too. They are cheap and have low insertion force. Same footprint, generally.
We only load the SMBs on engineering boards. We can always add them to a production board if needed, which is rare in this case. Sometimes we do leave them on production boards, like to pull out a clock for a scope trigger or something.
What I usually do to snoop a signal is something like
| | | | | 50r trace +--450R-----------------------(o) SMB | | | gnd | | |
With an 0805 or 0603 resistor, that's good to several GHz.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
be
similar to this:
and you probably don't need to solder the connectors in, I think with a bit of tweaking you could sorta press-fit when you need to measure
-Lasse
No stub effects in that case with GHz's ?
Never used MCX connectors ... i will give it a try tomorrow.
Best Regards, H
No, as long as you use a 50 ohm coax into a 50 ohm scope. It forms a
10:1 resistive probe. The trace from the snoop point to the 450r resistor should be very short.Without the scope connected, there will be a small reflection at the SMB, but it's attanuated twice by the 450r, so in most situations you won't notice it. 950 ohms makes a 20:1 attenuator, even less loading.
What I want to do next time is use an ADA4960 as a differential signal snoop pickoff, into an SMB or MCX.
MCXs are used in Cisco servers or something, so there's tons of cheap cables on ebay.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Nope. Its basically a passive divider HF probe.
-- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico@nctdevpuntnl (punt=.) --------------------------------------------------------------
That works, but can keep one hand occupied, which is a nuisance if you need to probe multiple points.
Agilent sells a 6 GHz resistive probe for $3134. You can make your own for well under 1% of that.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
That's exactly what i meant with GHz's (in fact very short rise and fall times) a small portion of a inch could ruins a PCB design.
Ok thanks a lot John,
Habib.
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