[Antennas] Old Coax

Thu, 12 Sep 2002 09:48:54 -0400

Larry, 

Coax does age and become more lossy with age.  Their especially shows
y=up when used at VHF and UHF frequencies.  The plasticizers used in the
plastic to make it flexible, contaminate the center insulator.  There
are non-contaminating types of coax available.  The useful life is
determined by measuring power into the coax terminated in a dummy load
and the power measured at the dummy load.  If you are satisfied with the
loss, it OK for your application. Most coax cable today are good for at
least 5 years. You may be interested in getting "the wiermans coax book"
or look at www.wireman.com  .The www.davisrf.com  site also has good
info on coax losses.

Your mileage will vary compared to anyone else's... 

Jerry 
W3CDE 

-----Original Message----- 
From: Lefczik, Larry D [ mailto:[email protected]
<mailto:[email protected]> ] 
Sent: Thursday, September 12, 2002 9:13 AM 
To: [email protected] 
Subject: [Antennas] Old Coax 

I've seen several times that coax cable should be replaced after a few 
years.  Why is this?  Is it just because of UV exposure to the outer
jacket? 
If so, is coax which is still on a spool good forever?  Is coax used
indoors 
subject to aging?  What about MIL-STD coax, is that less susceptible to 
aging?  

A lot of questions, but the main question is, why is it recommended to 
replace coax periodically? 

Thanks de WA2EHZ 

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