> For your application I'd use 1.5 IPS Sked 40 water pipe (1.9" OD) with
> the 4 bolt flanges (usually weld on) to couple them. Drilling/pinning
> is a potential problem area for wear in the years down the road.
At our last swap there was a guy selling Aluminum tubing, boom to mast
clamps, and mast coupling/clamps. The couplings were sizeable and appeared
to be very rugged. At something in the order of the mid $30 range each they
weren't cheap, but they appeared to be sufficient that I considered getting
a couple, but that was before I spend too much on other *stuff*. <:-)) I
have no idea as to who makes them or name of the outfit selling them. His
prices were a bit high on tubing and masts compared to Dayton.
I drill and pin, but the pins are virtually a press fit. OTOH the first one
I put in was a slip fit and within two years it sheared off. So... like
others I'd reccomend agains the drill and pin method. Having to climb "up
there" in the winter when it's well below freezing to redrill and pin, or
just replace the pin for a temporary fix is not at all fun. Welded flanges
work well, but might present a problem getting out of the tower if need be.
OTOH taking a 20 to 24 foot mast out the top of a tower can be an exciting
proposition unless you have a *tall* gin pole.
Roger Halstead (K8RI and ARRL 40 year Life Member)
N833R - World's oldest Debonair CD-2
www.rogerhalstead.com
>
> 73 Don
> VE6JY
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Bill Turner
> Sent: Saturday, September 16, 2006 3:24 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] Recommendation for mast on bottom mount rotator
>
>
> I'm going to move my rotator to the bottom of my 80 foot tower and would
> like recommendations for the mast. I will support it at the top with a
> thrust bearing, and at least one, possibly two, non-thrust bearings part
> way down to prevent side to side movement.
>
> My question is what would be a good mast material? It would only have to
> support it's own weight and I'm wondering if 2 inch water pipe would be
> suitable? How about 2 inch EMT? The upper mast section which actually
> holds the antenna is high-strength steel.
>
> I would drill and pin the couplers to keep them from coming loose. The
> antenna is a four element quad, about 65 pounds.
>
> Is there a better way? I want to do it right, so within reason, cost is
> not a factor.
>
> All suggestions appreciated.
>
> Bill, W6WRT
> _______________________________________________
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