I take it that the impedance measurements are being done on printed 
circuit boards.  I have been looking into the question of such 
measurements recently.

Here at Compunetics I have an HP 54120 scope and associated 4 channel 
test set.  I recently got several mounting jacks from M/A Com, part 
number 2062-0000-000, that offer a 50-ohm connection to the appropriate 
mounting holes on a board.  I expect these jacks to work well with a 
suitable coupon on the board edge.  They certainly seem sturdy enough.  
They can be screwed into a 50-ohm cable from the test set.  I also plan 
on terminating the coupon with a 50-ohm jack and a 50-ohm termination to 
get rid of reflections  there.

IPC-TM-650, method 2.5.5.7, may be of some help.  It is where I got the 
M/A Com part number.  

According to Alson Wong at Hewlett-Packard, not having a 75-ohm connector 
should not create a big problem if your test set is 50-ohms.  I can't 
speak from experience.  If you want to call him, Alson's number is 
800-452-4844.  He is in Colorado.

How do I find out more about the Polar instruments?  Do you have an 
address or phone number?

Louis Hart
[log in to unmask]


.

On Mon, 8 Apr 1996, ppannu wrote:

>      
>      
>      We are using couple of Polar CITS 200, to measure impedance of our
>      product.  These are truly wonderful machines intended for 
>      manufacturing environment.  The problem we are having is the test
>      probes, they are so fragile and have very short life, and the 
>      replacement is about $400 a piece.
>      
>      Has anybody looked at or found more robust probes for these testers?
>      The company looking into new design, but nothing to offer yet.
>      
>      Also, the company supply a IP-75 ohm and a IP-100 ohm Probes, in 
>      addition IP-50.  Do these IP-75 and IP-100 really make  difference
>      in test results?
>      
>      Thanks, in advance
>      
>      Zycon Corp.
>      [log in to unmask]
>