[TowerTalk] Plastic End Caps

[john at kk9a.com]

I agree that water inside a tube can freeze and cause it to fracture.  On 
all of my antennas the horizontal elements are open at each end so water 
does not build up, freeze and crack the tubing.  It seems to me that a cap 
would seal in the water.

John KK9A


To: TOWERTALK at contesting.com
Subject: Re: [TowerTalk] Plastic End Caps
From: "Jeff Carter"
Date: Mon, 21 Apr 2008 17:35:19 -0400


In the case of the Cushcraft R7, moisture ingress into the traps
equals VSWR of 10:1 or worse.  In the case of the A4S, insect nesting
and moisture can cause issues.  With both antennas, water in the
tubing can freeze in the colder months and the aluminum tubing can and
will deform and/or burst from the pressure, just like a copper water
line might.

This may not be an issue at all QTH's, but at mine, antennas made with
hollow tubing must be sealed against the environment.  Your mileage
may vary.

When purchasing end caps, be sure to deal with a vendor that does
*not* charge a minimum order fee.  The one I suggested was selected
for this very reason, all the others I've seen suggested will charge
you anywhere from $15 to $25 for the privilege of taking your order.
I would rather have something more tangible for my money since I am
not wealthy.  Those of you who are, be my guest.

Jeff/KD4RBG

---- Original message ----
>Date: Mon, 21 Apr 2008 17:12:07 -0400
>From: <john at kk9a.com>
>Subject: [TowerTalk]  Plastic End Caps
>To: <TOWERTALK at contesting.com>
>Cc: bmaser at tampabay.rr.com
>
>What is the purpose of end caps?    I never use them and I have never had a
>problem as a result of not having end caps.
>
>John KK9A