[NLRS] Time Domain Reflectometry...

[Dr. Gerald N. Johnson]

The two QST articles were May 1989 pages 22 to 24 and March 1973 several 
pages starting on page 19. The circuit in the May 1989 article has 
worked decently for me with a 200 MHz scope (Tek 475) for probably close 
to 20 years. I can detect 50 ohm N connectors in a run of 75 ohm coax. 
The 1973 article uses a pulse generator with a slower rise and fall 
which reduces the resolution possible. Ideally the scope is faster than 
100 MHz and the rise time of the pulse is shorter than the rise time of 
the scope. Even better then scope samples at a few GHz and the pulse 
rise time is super fast, but 100 or 200 MHz scope with the May 1989 
circuit works in the real world. Not perfectly, but works. The 1973 
article which I just looked over quickly having downloaded it from ARRL 
has much better scans of the scope displays and seems to explain how it 
works quite thoroughly with real examples.

I've attached both for Bud, though the reflector will strip them off.

73, Jerry, K0CQ

On 12/17/2010 3:31 PM, Bud Patten wrote:
>
>
> Hi Gang.  I've been looking for info on time domain reflectometry without much success.  I know that there have been articles published in ham magazines in the past but haven't been able to locate any of them.  If you have anything on the subject, I'd appreciate your passing it along.
>
> 73,
> Bud
> w0lcp
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