[50mhz] [VHF] Replacing coax

[Tim Marek]

12 years is a long time for a piece of "VHF" coax.... (used on VHF 
Fequencies)

The insertion loss goes up as the cables die.. and yes Coax has a shelf life 
like anything else. Their are likely many small cracks in the outer jacket 
exposing the shield to wicking up water causing impedance bumps and 
corrosion.Connectors over time degrade, often filling with water at some 
point in time causing... you guessed it... more corrosion.

What is more important to note are the intangibles that prey on the mind... 
"Would I have worked him if the coax and connector had been of verified good 
quality?" Maybe... maybe not... Testing coax loss isnt rocket science... 
but... the same amount of effort needed to get to the far end to test it can 
be used to replace it as well.

In the past when I was doing the VHF Contest's as a very serious Multi Op, 
Mountain Top, Portable... I would replace ALL the coax run's EVERY year, 
last years set became the spares, and the spares became my archived backup 
with the one they replaced (4yrs old) donated to a local ham club or 
individual.

Why did I do this every year? Those cables took a beating each contest 
season and when your trying very hard to break the existing all time W7 
record in the June contest, new feedlines are cheap insurance against 
failure in a key area of the station, your antenna system.

Now that is been almost 10 years since my last mountain top expedition, 
those cables here in the high desert of northern NV are showing signs of 
weather checking and probably could stand to be replaced.

Now this brings up a interesting question... What to replace them with? 
W/O a doubt, the most bang for the buck, most durable, well built, lowest 
loss, 50 ohm RG8 size coax out there has to be CQ-106 made by "The Wireman". 
That is the only cable I have used for the past 20 years after trying many 
others in the harshest places to operate from, the tall mountains of the 
American West. Its the only one to hold up, time after time.

As one who has been a hard core mountaintop contester since the 80s and 
worked in the 2 way field alot of years, thats my take on it. Your mileage 
may vary...

73s de Tim - K7XC - DM09nm... sk
----- Original Message ----- 
From: "John Geiger" <aa5jg at fidmail.com>
To: "50mhz" <50mhz at mailman.qth.net>; <6meter at yahoogroups.com>; "'VHF 
REFLECTOR'" <vhf at w6yx.stanford.edu>; <DX-IS at yahoogroups.com>
Sent: Tuesday, March 01, 2011 4:39 PM
Subject: [VHF] Replacing coax


>I went out this morning and did a visual inspection on my coax runs, and 
>they
> all look in very good condition. No cracking on the jacket at all, and the
> jacket still looks as good as when new.  One run of RG-11 I have is 12 
> years
> old, but still looks great.  I don't recognize any signal degradation on 
> the
> coax runs either, nor changes in SWR.  Now I don't have any complex test
> equipment to test the coax runs with, just a SWR/power meter built into my
> antenna tuner.
>
> Given that the jacket on the coax looks ok, and I haven't noticed any 
> change
> in antenna performance, is it safe to assume that the coax is still good, 
> or
> is there an age limit for coax after which it starts to deteriorate from 
> the
> inside?  Is there a rule of thumb on how often coax should be replaced?
>
> 73s John AA5JG
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