Tower is going up ASAP, without antennas for now. But just realized that
it will be MUCH easier to put up antennas if the mast and thrust bearing
are in place BEFORE the tower goes up (Appliance Operator Alert!!!). So,
I'm trying to find LOCAL sources for the mast and bearing.
MAST:
Planning on 8 feet of mast inside tower, and about 10.5 feet sticking out.
3 antennas on the mast:
ANT 1: ~ 1 foot above tower, C4XL, 9.6 sq ft wind load
ANT 2: ~ 5 feet above tower, future 6m beam, ~ 5 sq ft wind load
ANT 3: ~ 10 feet above tower, 13 ele 2m beam, ~ 1.8 sq ft wind load
I've described my installation to a few people and they've told me I need a
mast that will handle about 40000 to 46000 psi based on 85mph wind gust.
The best pipe I can find locally is 2 3/8" OD, 2" ID, Schedule 80
ungalvanized carbon steel (black iron) pipe for $2.35/ft, 21ft minimum. I
been told that this type of pipe can only handle 30000 psi. Correct? Good
enough? Maybe I can replace the mast whenever I get around to installing
that future 6m beam?
THRUST BEARING:
The local bearing shop can sell me a "SealMaster SF Series Standard Duty
Four-Bolt Flange Unit" which uses ball bearings. The owner claims that I
shouldn't need the roller bearing model since the ball bearing model is
designed to handle MUCH more weight than my ~200 lbs of antennas and mast.
(besides, the roller bearing model is not in stock). The 2 7/16" bore
model is $109.95 and is IN STOCK. (The 2 3/8" model is not in stock, which
would match my pipe's OD). Does it matter that there will be a 1/16"
difference between my pipe OD and the bore hole? Will the set screws make
up for that? (1/32" on each side?)
Your thoughts on this would be appreciated. To keep traffic down on the
reflector, perhaps you could reply directly and I can summarize. Both the
pipe place and the bearing place are open until Noon on Saturday, so your
comments today are appreciated.
73 - Scott KA9FOX
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Scott Neader, LAN Administrator Phone: 608-796-5032
Century Telephone, La Crosse, WI FAX: 608-796-5100
sneader@centuryinter.net Pager: 608-789-1493
http://www.wi.centuryinter.net/wicent
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