Date: Wed, 13 Dec 2017 12:37:52 -0700
From: David Gilbert <xdavid@cis-broadband.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] PST61 Rotor Reliability?
<THANK YOU!
<Finally someone understands.? I never meant my original reply about the
PST-61D to devolve into this lengthy discussion, but I couldn't let it
drop without the story being set straight.? My situation is indeed
peculiar ... possibly even unique ... but some physically erroneous
comments were popping up in some of the replies that needed to be corrected.
And yes, my options at this point appear to be either a PST-71D or a
prop pitch from K7NV.? I've ruled out the PST-110D for two reasons ...
one is simply the weight of the beast, and the other is the fact that
Pro-Sis-Tel apparently went to a Hall Effect position sensor for it.?
Here is WA7NB's experience with the PST-110D:
https://www.eham.net/ehamforum/smf/index.php?action=printpage;topic=105416.0
He ended up going with a prop pitch (don't remember which size).? I
emailed Array Solutions to get their side of the story on WA7NB's
issues, but they never responded.
73 and thanks again,
Dave? AB7E
## The small K7NV PP I have.. + its mating GH control box is dead
simple, point and shoot affair, with ramp up and ramp down features, etc.
## GH took a standard RT-21 control box, and modified it for the
small PP. It contains a single hammond xfmr and rectifier for the PP motor,
aprx 32 vdc un regulated, and with no load. Vdc drops of course, with the
normal
10A load on it. The small PP weighs LESS than my M2 OR-2800 and eats it for
lunch
hands down. The small PP has a stupid amount of tq, like > 1200 ft lbs.
Beauty
is, it hangs BELOW the rotor plate..and is bolted to the rotor plate with just
6 x
.375 bolts. The mast clamp is the ultimate, BUT they have to be configured for
an exact size OD. Mine is setup for my 2 inch OD x .375 wall thick 4130 CM
mast. He will make the mast clamp for any diam you want, like 1.9 OD up to
3.0 inch OD, or even bigger. The mast barely slides in. Once the 6 x mast
clamp
bolts are tqed down, the mast will not slip. Heck, I tested it with just a
pair of vice grips and
a rag to protect the finish..and no bolts at all. You barely pinch the mast
clamp,
and it clamps 360 degs around x aprx 6 inchs tall. IE: 2 inch od mast has
a 6.28 inch
circumference. And 6 inchs tall x 6.28 = 36 inches of actual surface area.
## with a 2.5 inch OD mast or a 3.0 OD mast, the surface area is even greater.
And any of the above is far better than the semi useless mast clamps used on my
OR-2800..and most other commercially made rotors.
## Ok, MAX rpm on the small PP is aprx .55 RPM. It takes 1 min + 50 secs
to rotate 360 degs. with the ramp up and down feature, it will turn a lot
slower
than that. You can also set any speed you want, or START the ramp up speed at
any speed you want. I bought a small PP back in 1977, it was the same .55 RPM.
## K7NV has modified the back end of the electric motor shaft, and installed an
arm with a magnet on it, plus a counterweight at the opposite end of the same
arm.
This rotating magnet whizzes past a fixed magnet, to produce the pulses.....
which are routed
to the GH box...which is programmed for the 9600 : 1 ratio. GH box can be
programmed for
any ratio you want.
## So u end up with superb digital readout down to .1 deg increments. It
doesnt get any
better than this. Lightweight, globs of tq, and ultimate mast clamp. Plug +
play. You just
require 6 x .375 holes in the rotor plate, all spaced every 60 degs. Rotor is
brought up from below,
and bolted to rotor plate. Mast clamp assy simply passes through the large
diam hole in the rotor plate.
Plenty of info and pix on his website.
Jim VE7RF
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