[TowerTalk] Taller tower, shorter mast or vice versa?

[Tower (K8RI)]

I have a mast extending 30 feet above the top of a 45G which is at 100 feet.
I use two thrust bearings to eliminate any side loads on the rotor which is
a PST-61.

To work on the antennas http://www.rogerhalstead.com/ham_files/Tower29.htm
I move the rotor out the side of the tower, loosen the tribander mounts,
then using a 20 foot comealong I lower the mast down through the tower until
the 6-meter beam is just above the tri-bander.  To get to the 144 and 440
arrays, I have to loosen the mount for the 6-meter beam and let it set on
top of the tribander. I then get a new bite with the comealong and lower the
mast down to a point where I can work on the 144 and 440 arrays.

The above operation takes about an hour.  It takes another hour to put them
back up into position.


> 20' of mast out the top of a tower is not only a big strain on the mast,
> but also on the top of the tower.  Be sure that the tower, bearing, and
> rotor combination can handle what you want to put up there.  It is also

At 20 feet I'd add a second thrust bearing as that makes one very big lever
which translates to a lot of side thrust at the rotor with the single thrust
bearing acting as the pivot point.

> much harder to service if you don't have a bucket truck handy... in fact
> any more than as high as you can reach standing on top requires much
> more work for installation and maintenance.  I would consider things
> like ring rotors and side mounted fixed antennas before trying to push
> up 20' of mast with antennas above the top of any tower.

Where there's a will there's a way, but every extra foot properly supported
translates in to lots of extra money.   Going 20 feet above the top with a
mast is really going to require at least a 30 foot mast and that mast is
likely to be more expensive than ROHN 45G sections.
That means 20 feet above the top is worth 3 tower sections.

Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair (S# CD-2)
www.rogerhalstead.com