RE: [hex-beam] Hex on Tower
- Hi Mike:
Re rotator near tower bottom:
Many of us have done this in Calgary using self supporting towers to take the torque load off the top section. I had this setup using 1-1/2 inch steel tubing inside the tower and 3 copper bushed triangular "spiders" (made from ready rod and 2in pipe) and a 6 ft top mast with thrust bearing on a 53 ft tower. Just a TH3 would really twist the tubing -about 10-15 degree swing in bad winds. Nothing broke over 25 yrs. but the coupling pin holes sure got larger :(
I would not repeat the exercise for the hexbeam as it is symmetrical and has lower mass. It is a lot of work, adds weight and wind load to the tower even more than a small rotator at the top. Not to mention the pain of putting 20 ft pipes inside the tower - or even doing multiple couplings for 10ft. pieces.
My Delhi MD56 is similar to your BX I believe - stamped triangular 8 ft sections.
I would not try 3/4 EMT even for a 10 ft tower (you did not say your height) as it will just twist up.
If you want more details about my old setup, email me.
From: email@example.com [firstname.lastname@example.org] On Behalf Of Mike Heiler [cq52simplex@...]
Sent: Sunday, July 24, 2011 9:37 AM
Subject: Re: [hex-beam] Hex on Tower
I should also mention by placing the rotator in the ground section you do
not need to run heavy mast all the way down to the rotator. I have sections
of 3/4 inch EMT (electrical conduit), you can reduce size because all the
weight is above the top thrust baring, and you will only have the twisting.
To connect the sections together I drill holes at each end and connect them
with a larger pipe . also instead of using a 2nd thrust baring on the 2nd
plate I have thought of drilling a hole though the mast, run a bolt though
with 2 small caster type (wheels) and have them take a lot of the
weight.again. I am cheep. I like to keep it simple.
On Sat, Jul 23, 2011 at 11:36 PM, Gary "Joe" Mayfield <
> **[Non-text portions of this message have been removed]
> Hats off for identifying the AX tower. They used to be a fairly
> common TV Antenna tower, but folks often confuse them with BX which is
> stronger. The dimensions also do not jive with from AX to BX tower making
> comparisons difficult. I am wondering what other antennas you plan to put
> on the tower. The Hex is fairly symmetrical and should put much of a twist
> on the tower. On the other hand a classical tri-bander can put a great deal
> of twist on the tower due to its shape.
> You may want to check your area's wind requirements which can be
> found here
> The Rohn catalog has changed over the years as to how much antenna
> can be placed on a 30' freestanding 25G tower. That data is also available
> on the web here
> I hope this helps!
> Joe kk0sd
> -----Original Message-----
> From: email@example.com [mailto:firstname.lastname@example.org] On Behalf
> Of Ernie
> Sent: Saturday, July 23, 2011 1:56 PM
> To: email@example.com
> Subject: [hex-beam] Hex on Tower
> I am in the planning stage to put up a tower to transfer the K4KIO hem from
> its present 20ft push-up mast and would like to know if anyone has any
> experience with the earlier model Rohn AX series towers (note: NOT the BX).
> At a height of 32ft with top section at 14" each side and the bottom at
> approx. 26" each side but with fewer # of X braces than the BX series, I'm
> concerned about the twisting motion on high winds.
> Another alternative will be to put up a 30ft Rohn 25G freestanding on a 4 x
> 4 x 4ft concrete base. If I go this way the tower will not be bolted to the
> house eve which I am avoiding. Any and all inputs will be much appreciated.
> de Ernie, AD5MD
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