KC8QVO, Steve said:
" . . . Also, what does everyone recommend as a mast? Array Solutions sells
some REALLY NICE PE certified masts, but they are VERY expensive. I was
thinking about going to the plumbing supply store and getting a 2" galvanized
steel pipe. . . . "
In a direct communication to Steve I had suggested 2 inch o.d. galvanized pipe
which is 1.5 i.d. inch water pipe. The 2 inch nominal is actually 1 and 7/16
inches which means that the walls are 1/4 inch or 7/32 inches. The stuff is
bullet proof and a 15 foot spliced piece with two VHF and two HF beams survived
a wind event that pulled my tower away from the house and twisted the two lower
sections of tower. The antennas, top two sections of tower and the mast are
still pristine and in use.
I use this pipe because 26 years ago, HyGain used it as their "gold standard"
when describing the process for shimming a mast in the Ham IV rotator. I do not
use the new stuff --I priced it today, it is $33.00 per 10 foot section. I go
to a salvage yard and get used 1.5 inch pipe. It may have rust on the inside
but I have found that pipe with no external pitting or rust is as strong as new
and only runs 40 cents per foot. It is sold by the pound at the junk dealer.
When it is necessary to splice in order to get a desired length, I take the
pipe to a hardware store and have them extend the threads beyond the standard
for a water seal. This in conjunction with a standard coupling gives plenty of
purchase to give a strong joint. Once assembled I drill through the coupling
and pipe and install tension pins (roll pins) to prevent the joint from
unscrewing. (It did happen once!)
The down side is that the stuff is heavy. However, I have a Glen Martin Hazer
on each of my towers and I am working from a roof top or from the ground. Easy
enough to use a block and tackle on the tower to lift the mast above the Hazer
and lower it into the bearing. Of course once it is in place, weight is a non
issue.
73, Sherm KB9Q, (EN52vv)
swanson-KB9Q@ticon.net
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