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Re: [TowerTalk] Condensation inside LMR-1200 + 7/8" heliax ?

Subject: Re: [TowerTalk] Condensation inside LMR-1200 + 7/8" heliax ?
Date: Thu, 2 Dec 2010 06:26:04 EST
List-post: <">>
Hi Jim, I have experience with 7/8" Heliax water condensation inside the  
center conductor. In my case, I found that wrapping the center pin threads 
with  a couple of layers of teflon plumbers tape before installation stopped 
the  problem.
I don't know if that merely kept the water inside the center conductor or  
actually stopped the ingress of water vapor which prevented collection of 
water  droplets. In either case, it stopped the problem.
In commercial systems, they pressurize the coax with dry air or nitrogen  
and the positive pressure keeps water vapor out of the cable. Apparently the  
center conductor is also protected with this procedure.
The positive pressure prevents the back and forth flow of water vapor  due 
to heating/cooling cycles and this stops the accumulation of water  
Can't comment on LMR1200, no experience with that.
Gerald K5GW
In a message dated 12/1/2010 9:37:36 P.M. Central Standard Time, writes:

OK,  what's the procedure to prevent condensation  from  forming   inside 
the center conductor of either LMR-1200  [which uses a hollow cu  tube for a 
conductor].... or  ditto  with 7/8"   heliax ?? 

Are we supposed to blow  dry nitrogen / dry air / hot  air  down the inside 
of the CU tube 1st..for a few minutes, before  installing  7-16 dins on 
each end ? 

My thought was if any high  humidity air was 1st blown out, before 
connector's  installed, coax  installed, and connector's are water proofed, then
we should have minimal  problems down the road. 

Is my plan a waste of time ?   

Later.... Jim   VE7RF  

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