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#1
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Dear antenna pros, I've always taken it for grunted about the 300/75/50 ohms of TV ribbon, coax, etc. But how does one measure it? My ohmsmeter doesn't budge. Is there some standard formula, like wrap grandma 100 times, with the far end connected to a cheeseburger in her mouth, the near end finally displaying the characteristic 300/75/50 whatever ohmses? You don't measure it with most instruments you would have . It is a calculated value from the size and spacing of the conductors and the insulation between them. There are ways to measure it but most would not have them. Here is a place you can go for an explination. http://www.epanorama.net/documents/w...impedance.html |
#2
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Howdy,
These numbers are characteristic impedances of the cables. If you had an infinite length of it all you would have to do is use an impedance meter and it would yield the correct C. I. It is a function of the frequency and the distributed R, L, C, and G of the cable. The ARRL Handbook and their antenna book can tell you much. 7e de Jack, K9CUN |
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