[TowerTalk] rotor comparisions

Tower (K8RI) tower at rogerhalstead.com
Thu Mar 25 22:09:55 EST 2004

Oops... You also asked why.

The PST-61 is rugged, requires no brake and has no play.

The HDR 300 requires a brake, the brake switching is really odd ball in that
you have to manually turn off the brake and then turn the antenna. The
output shaft turns relatively easy with the brake off.  Turning the brake
off in high winds means the antennas are going to weather vane "right now".
Then at the least you have to dismantle the rotor and get it back between
the limit switches.

> Which is better and why?M2 2800 or whatever they call it now,Prosisteil
> PST-61 or Hy-Gain HDR-300.Looking for a stout rotor to turn some big
> of uhf beams in a high wind area.I have a PST-51 up there now but I keep
> shearing off the "pin" bolt and I don't want to put a bigger one in and
> break the rotor.Plus I think the bolts that hold the rotor plate to the
> rotor are getting stretched which means it can turn 20 dergrees or so back

Fix the bolts and you won't be shearing off the other bolt.  Those rotor
plate bolts have to be solid.  Mine is keyed and bolted to the shaft with 4
bolts in the plate.  Any play in the system puts a tremendous load on not
only the rotor, but the whole tower when it comes up against the stop.

I have on the order of 300# worth of masting plus a TH-5 at 100 feet, 7L C3i
at 115 feet, and 2 11-L  440s  and 2 12-L 144s on a 14 foot cross boom at
130 feet.  70 MPH plus winds a couple weeks back caused the mast to slip
about 10 degrees in the mount, but nothing broke. I just have to go back up
and realign things.

> and forth and then that puts a lot of torque on the "pin" bolt and then
> it breaks.The "pin" bolt is grade 5 3/8*4 with a grade 5 cap screw.It does
> indeed break as to just getting lose and then fall off.  Gregg  K9KL

It only takes a few degrees of play to shear bolts in winds far less than
the system design.
I had mine shear off some 5/16 ths stainless pins in the mast.  Reamed the
holes and put in 3/8ths (tight fit).  I think I got those sizes right.  I
haven't been up there since late last Summer.

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