"Irv Finkleman VE6BP" wrote in message
...
Channel Jumper wrote:
Unless there is something special about this coax, or if you are just
going to use it for a television antenna, or something that you are only
going to receive on - THROW IT AWAY!

Like others has said, there is no way to predict what will happen when
you go to use it unless you attach it to a Time Domain Reflectometer and
sweep it! Something I doubt most hams would have - unless they work in
the cellular telephone industry.

No one can predict, but there is intelligent guesswork. A TDR might tell
something, but putting the coax in a live situation usually works well
enough for ham radio purposes.

I run an amateur radio station, and if everything had to meet mil-spec I
wouldn't have had much. I did have my trusty MFJ-259B SWR analyzer, which
while it is not necessarily as a TDR, did serve me well, and as far as the
coax which led to this discussion goes, it did test OK when
fed into a dummy load over the HF bands.



The criterea which I lived by over 56 years of ham radio was 'did the
signals sound good, and could I make contacts?' -- and using old
hand-me-down wires and cables, and reusing various connectors I was
totally satisfied. It was ham radio on a budget -- I would hever throw
out something I might have been able to fix up and reuse. It kept me
very happy over the years and I'm not about to change now.

My two bits worth.

Irv VE6BP


For ham use I agree, ues whatever you can get. If it is difficult to
install, then go with new stuff. I put up a tower with 4 beams stacked
above each other. Due to the difficulty in doing things over, I would not
use anything but new coax. I did mount some antennas on the side and used
some old coax as it is not difficult to replace it if it is not any good.

I have a 50 foot piece of some foam coax that is over 45 years old. It
spent about 20 to 25 years outside in use. Then just stored inside. I have
a spectrum analizer and tracking generator and swep the frequency from 1 to
1000 MHz. It seems to meet spec to about 30 MHz and then it starts to have
more loss than it should. As I get to around 400 it starts to fall off even
more.
I have not cut it open to see if the coax seems to have had water in it or
not.

A repeater I keep up started getting desense and other noise. Checked the
jumpers from cavity to cavity and found they were the problem so replaced
them. They were about 30 years old and had been in use inside a builden
that was not heated or cooled.





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