I always drill a small drainage hole (about 5/32) on the bottom side of my
booms just inside of where the end cap stops. I do not seal the element
ends... dirt-dobbers around here do that within a week. I also seal off the
top and bottom of my masts, drilling a small drainage hole in the bottom
mast cap. I do this to keep wasps out of both ends of the mast. Marine
dealers carry a device known as a "Bearing Buddy"... a replacement for the
axle bearing dust cap... used to keep the axle bearings packed and under
constant pressure. They also sell a vinyl cover (cap) for these Bearing
Buddies called a Bearing Buddy Bra... to keep grease from slinging onto the
wheels. These are excellent for this job, come in black and in a variety of
sizes and hold up to sun and salt water for years. I have some in use today
that have been in service for over 20 years... and they still look and feel
fine. My Yagis do NOT go braless!
----- Original Message -----
From: "K4SAV" <RadioIR@charter.net>
Sent: Monday, April 21, 2008 8:09 PM
Subject: Re: [TowerTalk] Plastic End Caps
> While I was waiting for my tower to be finished, my XM240 was sitting
> out in the back yard on concrete blocks for about a month. When I
> removed the end caps, a whole bunch of water flowed out. Draw your own
> Jerry, K4SAV
> email@example.com wrote:
>>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.
>>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
>>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
>>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.
>>---- Original message ----
>>>Date: Mon, 21 Apr 2008 17:12:07 -0400
>>>Subject: [TowerTalk] Plastic End Caps
>>>What is the purpose of end caps? I never use them and I have never had
>>>problem as a result of not having end caps.
>>TowerTalk mailing list
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