From a 2017-06-10 comment regarding a Weston capacitance meter on FB group vintage test equipment
Reminds me of the ” kicker” meters the phone techs used on the phone lines. There was a polarity switch that reversed the pair, and the tech could tell about the line from the kick the meter needle gave when the polarity was reversed. The capacitance and hence the charging current depends on the length of the line. If the tech knows the line is ten thousand feet long, it’ll kick more than one that’s only 2 kFt. Or if one conductor to ground kicks less than the other, that conductor may have an open along its length. Or it might show constant meter current, indicating leakage. The meter used quite a bit of voltage, 45 volts or so.
All the thousands of lines on my campus were under a few thousand feet, so it didn’t kick much at all. But just for grins, I punched down several jumpers on both ends of a 1200 foot cable, until I had a line probably 2 or 3 miles long. The signal just looped back and forth between the two ends, until it came out right near where it started. I was sort of like the phone phreaks, who would call themselves from all the way around the world just to hear the delay. The cable I was using had more than a thousand pairs, hundreds weren’t being used, so I could have made a pair that was a dozen or more miles long. But long before that, the losses would have been so high that the signal would be very weak by the time it returned to me. But it was fun trying. 😉
