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[TowerTalk] Underwater coax

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Subject: [TowerTalk] Underwater coax
From: wa9als@starband.net (WA9ALS - John)
Date: Tue, 23 Oct 2001 06:59:33 -0500
I don't want to start a debate about whether this is a good idea, or which
coax would be best.  However, I would like some ideas about how to handle
the points where the coax enters and exits the water.

I'm going to run a feedline across a pond that the top 10-12 inches of which
freezes each winter.  Someone said I should use some PVC where the coax
enters and exits the water to relieve compression forces at the freeze line.
I can't picture how to do this - Seems like if I just put a PVC pipe there,
it will fill to the surface level with water, and then that water inside the
PVC will also freeze.  And it seems the compressive force from the ice
outside the PVC would translate through the pipe, through the ice inside of
the pipe, and finally to the coax.  Is there something I'm missing about how
to do this with PVC pipe at the entrance and exit points?

I suspect it would be functional for "quite a while" if I just let the coax
take whatever nature has to offer, and it will be easy to replace if needed
every few years (except for those "crappy PL-259s"!).  But if there's
something reasonable to do to protect it some more, I'd like to do it.

Please read the first paragraph of this again, and then I'd be grateful for
any constructive ideas.  Thanks!
------------------------------------------------------------
John - WA9ALS - VP5RY

     email:  wa9als@starband.net
  homepage:  http://www.qsl.net/wa9als (New - NCJ article on VP5 trip)




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