I've used thin wall EMT for mast. The EMT, however, is not intended for a
rigid mast but the alloy is made so that it can be easily bent in order to
hug the wall and have wire ran through it. Not a good material if you want
it to stay put. But like I said I've used it and still have a mast up with
it.
I wasn't able to find any good lightweight mast so I took the thin walled
EMT, found right next to it at Home Depot some of the cheaper plastic
conduit and matched up what size plastic would fit inside the EMT. Starting
with the 2" EMT, I whacked off 2 feet of the plastic conduit, covered it
with epoxy and inserted it inside the EMT. Then I took some pressure
treated deck wood and ripped it down so that it would fit inside the plastic
conduit and applied the epoxy. Again, leaving 2 feet off the end. This
gave me 2 feet of space to nest the next larger section into it.
I used 2 of the 2" sections, welded them together with a conduit connector
and overlapped them inside. Then added 3 more sections to the top of that
by nesting them. Mounted the whole thing to the side of the house near the
top, added a pivot and about 250 pounds of lead weight to the bottom and
turned it all into a tilt over. Had to add a gin pole to the side to
support the lead weights at the bottom and the mast when tilting it over. I
use a block and tackle and another pole at the top of the house to attach
the block. Kinda strange but it all works and it's mostly just the cheap
EMT.
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Jim Brown
Sent: Friday, June 05, 2009 6:02 PM
To: Tower Talk List
Subject: [TowerTalk] Rigid Steel Conduit as Mast?
I asked a colleague who builds a lot of commercial two-way
installations where I could find 2-inch hot-dipped galvanized mast
material locally. He suggested that I use 1.5-inch rigid steel
conduit. I'll be using a 10 ft length with a 3-element SteppIR (no
30/40M element), with roughly 3 ft inside the top section of the
tower. The tower is in a relatively protected location, so not a lot
of wind speed.
I would question whether this is sufficiently robust for a bigger
antenna, but this is not a lot of load. Any thoughts on this?
73,
Jim K9YC
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