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Re: [TowerTalk] coax seal

To: towertalk <>
Subject: Re: [TowerTalk] coax seal
From: Steve Maki <>
Date: Wed, 13 Dec 2006 23:47:40 -0500
List-post: <>

Like you, I can tape up a connection with 33 that is positively 
hermetically sealed. Many folks can't seem to however, and that is one 
reason why, in the commercial world, the standard has developed to be 
one layer of vinyl (the courtesy wrap), then one layer of butyl, then 
one or two layers of vinyl to hold it all in. The courtesy wrap allows 
the whole mess to be slit with razor knife and removed in about 20 seconds.

One nice thing about the latter method is that it is easy to use on very 
irregular diameters - i.e. a 1/2" to 1-5/8" junction. That's difficult 
even for me to do with just vinyl because there's not enough stretch 
available. If all I have is a roll of 33, I can make it work by 
carefully *tapering* the diameter with LOT'S of tape (like half a roll).

A favorite method of mine for ham work is a layer of (already mentioned) 
self fusing tape - Mocap, Plysafe, or just about anything with lots of 
stretch - and then a layer of casually applied vinyl for UV protection 
and to make sure it stays put.

Steve K8LX

Jim Jarvis wrote:
> This stuff is insidious.  There is no evidence that
> it results in a superior wx seal to two layers of 
> scotch 33 by themselves.  At least, none that I've seen,
> and no empirical evidence in its favor.
> In fact, I had ONE connector which was wet internally, when
> I finally peeled off the tape and coax seal, to get at it.
> No idea where the moisture came from, but it was there.
> What I do now is use scotch 33, wrap it tightly in one direction,
> with 50% overlap.  Then, I break it, and wrap it again, with
> the warp in the opposite direction.  These connections have 
> lasted longer than the antennas to which they're connected,
> with no wx problems.  The tape must be warm enough that it
> stretches a bit, and becomes conformal.  
> n2ea


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