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Old June 7th 09, 05:31 PM posted to rec.radio.amateur.antenna
Richard Clark Richard Clark is offline
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First recorded activity by RadioBanter: Jul 2006
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Default A reasoning on coaxial cables

On Sun, 7 Jun 2009 09:35:15 +0200, "Antonio Vernucci"
wrote:

the 0.8 ohm per meter figure was not taken a by a catalog. It simply comes from
dividing the measured DC resistance of my RG-179 cable roll (which is 25 ohm)
by its length (which is 30 meters).


Hi Tony,

Then you are suffering from one of two problems:
1. Your measurement is seriously in error, or
2. Your cable is from a very poor vendor, or
3. You have reported the wrong type of coax.

All that aside, the reason why it is specified as any specific Z has
been well described. If you take issue with any "one" measurement of
R that seems to confound those descriptions, then "any" measurement of
R would do so, likewise.

In other words, ALL cables exhibit the loss of R. There are coaxial
cables that are very much smaller than yours that are employed in
transducer probes for doing ultrasound scans of patients. You would
need a microscope to measure their dimensions. And they have enormous
loss.

73's
Richard Clark, KB7QHC