[TowerTalk] PST61 Rotor Reliability?

Rob N1KEZ rob at n1kez.net
Fri Dec 15 10:44:19 EST 2017

I have the PST-71D with GH controller. Optibeam 12-6 at 65Ft on the tower. Tower is on the crest of a 650ft ridge where the winds occasionally can be gnarly.  No problems identified so far. 

73 & gud DX
Rob de N1KEZ 
Sent from my mobile device. 
Please excuse brevity and errorz.

> On Dec 14, 2017, at 10:26 AM, Jim Thomson <jim.thom at telus.net> wrote:
> Date: Wed, 13 Dec 2017 12:37:52 -0700
> From: David Gilbert <xdavid at cis-broadband.com>
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] PST61 Rotor Reliability?
> <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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