Compact connector (and cable) for screened 50 ohm diff pair.

In situations like this, my policy is "make it their problem." Tell them to decide on a connector and cabling system, with all part numbers and assembly directions. When they don't do that, and are out of time, you can tell them what to do. I'd suggest something standard and cheap, USB or SATA maybe, so you can just buy cables.

The 33R is a little weird. You'll need to terminate at the actual cable differential impedance on your end.

You could use edge-launch SMBs and two RG174 cables, but a standard diff cable would be easier.

It's surprising how well "make it their problem" usually works, in all sorts of situations.

John

That's what I thought, but they want non application specific solution!

I think I might put a bit of effort into talking them round here, something like this is probably the best solution.

There's provision for 50 ohms between the pair at the ADC (not fitted).

I don't know if they want to experiment here, I'm just following the spec.

As someone said, things would be great if it wasn't for clients (and employees).

Thanks for the feedback John, that's another pint I owe you (proper UK pint, ie 568ml)!

Nial.

If it would be indelicate for you to tell them that they're idiots, I could do it for you.

John

He who pays the piper doesn't get called an idiot.

They are worked on slowly so they decide that it's their idea in the first place.

:-)

Nial.

Yup, that works too.

John

How about a... stereo audio jack? And for the cable, screened twisted pair?

(Though I've read in this NG, and other places that twisted pair's fields extend outside the cable, the implication being you should not use it near lots of metal objects.)

Such a cheap connector might not meet the following requirement:

But if they are asking for 33 ohm resistors, instead of... what is it... two 37.5 ohms normally? perhaps they're not too worried about ideal terminations.

It sounds like they have partial knowledge of the subject, or have not had time to think through the entire system, and are in a blame-avoidance culture and want you to tell them what will work.

s.

You might look at a mixed signal D connector - the standard "sub- minature" D-connector shells accomodate coaxial inserts, very silimar to SMB connectors. Farnell stock the Harting range

You will have to poke around the web-side to find the dimensioned drawings of the D-connector shells, but they are there, and it looks as if they ought to fi tinside the space you've got.

-- Bill Sloman, Nijmegen

Thanks Bill,

That looks like another possible solution, I'll look into it.

Nial.

Careful: the coax-insert D-subs are very expensive.

At 200 MHz, a regular d-sub would work, but you'd probably have to make your own cables.

USB or SATA are the way to go. Or even shielded CAT5 and RJ45 connectors.

John

The client has said he's past experience with these and doesn't like them, he thinks they aren't reliable enough.

Most RJ45 sockets are tight height wise but I agree with USB / SATA.

I'm working on them.

Nial.