Advice on measuring WC Ternination

[Chris Kress]

Would anyone be so kind as to recommend a means of building a word clock termination meter. I would simply like to verify that each of my word clock lines achieves termination at 75 Ohms. I have a radioshack multi-meter. I am hoping that it involves making a special cable and then measuring. But I would hate to blow anything up..

Anyone care to help out? Thanks

[tINY]

A hand-held multimeter isn't going to be able to measure anything like word clock signals.

You need a TDR, SWR meter, or a network analyzer of some sort. You may get by with a burst generator and a scope, but measurement is tricky.



-tINY

[Doc Mixwell]

Get a Big Ben, It tells you whats terminated and whats not.

Sorry....I had to.

[Chris Kress]

Originally Posted by Roc Mixwell

Get a Big Ben, It tells you whats terminated and whats not.

Sorry....I had to.

I sold my big ben because it made all of my converters sound so harsh. The only thing I miss is the WC termination indicator and I kept it around a long time just for that.

But, I am surprised that it is that difficult to measure the impedance of an electrical circuit. ?

[mpdonahue]

Originally Posted by Chris Kress

I sold my big ben because it made all of my converters sound so harsh. The only thing I miss is the WC termination indicator and I kept it around a long time just for that.

But, I am surprised that it is that difficult to measure the impedance of an electrical circuit. ?

If all you want to do is look to see if the signal is being terminated, get a decent scope and a couple of BNC "T" connectors and look at the waveform of the square wave at the receiving end. If there is a lot of ringing and the signal is 5v peak to peak, it's not terminated.
Also, if you take an external 75r terminator and a second BNC "T" on the front of the scope, by looking at the voltage drop with and without the external terminator you can determine if the signal is being double terminated.
All the best,
Mark

[peeder]

Originally Posted by Chris Kress

I sold my big ben because it made all of my converters sound so harsh.

Serves the salesman right for wading in over his head.