Re: P6137 scope probe repair


Tom Lee
 

Your doubts, fortunately, are misplaced. As a former boss of mine used to say, "An ounce of data trumps a pound of opinion." I have ounces of data.

Probe cable is lossy by design, to be sure, but that does not preclude good enough measurements to locate (approximately) a break in scope cable. It's a lossy structure, but so what? Good bridges will successfully measure the capacitance of a lossy capacitor. Within limits that vary from instrument to instrument, they'll give you the dissipation factor or Q, too. TDRs will show a small, but discernible bump of a discontinuous lossy line. Remember: We don't need to make an NIST-traceable measurement of the impedance per se. We're just trying to do well enough to find the location of a discontinuity. Don't conflate the two tasks.

Cheers
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 1/16/2021 05:37, Jean-Paul wrote:
Hello again

Doubt if TDR or bridge gives any useful information

Just look carefully and try to flex every inch, you can find a mechanical or visible flaw, often near the ends.

It is easier to buy some new ones than to find the cable.

Bought many over the years via epay about $35-70 ea, mostly in liked newsletter condition.

Bon courage

Jon




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