Hi Dave -
Your reasoning appears to be logical. However, internal rusting may
actually be enhanced by using caps.
The air in the tower legs is heated during the daylight hours causing some
of the air to move through or past the rubber membrane. At night, cooler
moist air is brought into the legs in the same manner. There is a good
chance that water/moisture will accumulate in the legs of the tower after
some time and cause many problems...Especially during sudden freezes and thaws.
Let the tower breath!
Rohn 25G towers are made of good "stuff." I can show you a 70ft Rohn 25G
tower that has been standing (guyed of course!) for over 25 years and there
is no sign of rust on the tower or any part of the tower. The tower it high
on a hill in Northern Westchester county, NY.
The use of the plug on the top section may not be such a great idea either.
It too has to allow air to move through it. A section of hose clamped to
the tower may change the resonant frequency of the unit to stop the
bothersome hum/whistle...Or teach it a tune that you like!
73,
Jay/AF2C
At 10:02 AM 10/16/97 EDT, you wrote:
>Hi Dennis,
>
> I cap mine because I worry about internal rusting as well as ice.
>I used pieces of a truck tire tube held on by a stainless steel hose clamp.
>(The rubber deteriates every few years, but a junk tire tube is usually free!)
>
> Besides those concerns, any open pipe will have a certain resonant
>frequency which will cause a hum when the wind blows across it at a particular
>speed. The hum can be quite annoying! For this reason I also cap the mast
>(using an adjustable rubber plumbing plug - which I have never had to replace).
>
>73, Dave Clemons K1VUT
>
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