Date: Tue, 31 Mar 2015 14:40:09 +0000
From: Markku Oksanen <ww1c@outlook.com>
To: Keith Dutson <kdutson@sbcglobal.net>, "towertalk@contesting.com"
<towertalk@contesting.com>
Subject: Re: [TowerTalk] Loss of wet RG-213
Hi
Interestingly I can't find any figures for the loss!I can imagine that high F
this may be really bad but how about 28 MHz?
Markku
## temp install a bird wattmeter at the top of the tower. Then another in the
shack. Then apply exactly 1 kw..if using a 1 kw slug,
or 1.5 kw if using a 2.5 kw slug. Then measure what you get at the top of the
tower on the freq of interest. Aside from the normal
water proofing of your choice, you should also use some form of a drip loop.
## back when I was 16, I had a hb 20M GP up 70 ft, fed with 58-U..and NO
connector at the base of the GP. I used the ARRL
fubar method of hot side of coax to GP..and braid to the 6 x radials. Then a
bunch of tape and goop. 4 months later... I had water coming
out of the coax connector in the shack !! The water had migrated down the
entire length of the braid ! Lesson learned. The same silly fubar
method of connecting coax to a quarter wave sloper on a tower, is still
depicted in the arrl ant book today...but even worse, with braid
attached to tower leg with a SS hose clamp ! A simple L shaped aluminum
piece, aprx .25 inch thick, with the hole in it for a SO-239
on one side, and bolted to the trylon tower leg on the other side... is a
better method. Then water proof the connectors plus where the
10 ga stranded RW-90 is soldered to the SO-239.
## Coax is expensive enough as is... esp the double braided RG-393 stuff.
Vapor wrap, plus T+B industrial heatshrink tubing... the
good stuff with the glue glop and ribs on the inside will water proof anything.
Then wrap the heat shrink with 88 tape.
Jim VE7RF
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