>I think the characteristics of so-called WD-1 surplus phone line varies. > FWIW, the two short samples of WD-1 that I have here are as follows: > > 115 ohms impedance, calculated from the following: .033 diameter > (averaged), .0685 spacing. The dielectric constant of the insulation > (polyethylene) is 2.2.
By sweeping it with a carbon 250 ohm pot on one end, and a SWR meter on the other, we can find a resistance value that results in minimal SWR change. Then, by measuring pot resistance with a ohmmeter, we know one thing about it. An impedance error of 20 ohms on a 100 ohm line is as meaningful as an 80 ohm error on 400 ohm line. By measuring attenuation of a reasonable length on several HF frequencies, we could know loss. That would take minimal work and equipment, but a good method. The problem probably is there are so many types it might change between types. I just wonder why no one has ever measured anything. _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
