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Subject: Re: [TowerTalk] WHICH ROTOR TO USE?
From: Demo <>
Date: Tue, 08 May 2012 13:03:30 -0600
List-post: <">>
Alfaspid  Rotators
Don VE6JY  is one of 19 hareholders.


On 5/8/2012 05:44, Jim Thomson wrote:
> Date: Sat, 05 May 2012 20:17:52 -0400
> From: K8RI<>
> Subject: Re: [TowerTalk] WHICH ROTOR TO USE?
> The Orion 2800 was one of the other rotators I was trying to think of
> which I believe uses a double worm gear drive and pulse direction
> indication.
> ###  The OR-2800  does NOT  use a double worm gear drive.  It’s
> just a single worm gear drive.   While the upper clamp on the OR-2800
> may well look massive and heavy duty, its junk, toss it.  The teeth will
> not bite into anything, esp  heat treated chromolly steel or DOM.
> Replace it  with either the clamp assy from K7LXC... OR the
> one from kurt Andress, K7NV.   The one that Kurt makes for
> the OR-2800 is the same design as what he uses for his prop
> pitchs.  IE: they pinch the mast almost a full 340 degrees.  The surface
> area is just massive  vs the tiny amount used on the teeth of the oem
> clamp.
> ##  The OR-2800 control box is fubar..although it works.  The GH
> box blows it away hands down.
> The Canadian built, AlphaSpid is a great rotator that I believe fits
> inside a 25G has rotational torque of 3200 inch# and holding torque of
> 14,000 in #
> Price was roughly the same as the Ham IV with a digital control box or
> about $1200. With the current exchange rate I'd guess it to be some
> where between $1400 and $1500. OTOH I've not heard much about them for
> a while. They are "I believe" sold stateside by MFJ.
> ##  My understanding is the Alpha Spid is built in Poland,and that Don
> Morman, VE6JY, owner of Alpha radio, is just the importer and distributor
> for them.   MFJ is now the US distributor.
> ##
> ## here is a list of dealers world wide. 
> ##  exchange rate is at par  between US and Canada.  If you are in the usa, 
> you
> may as well buy one from mfj....and cross your fingers.
> ##  I would take all these rotating torque numbers with a grain of salt, since
> most are pure BS, when actually measured.   We have all sorts of nonsense, 
> ranging
> from...  start up torque, running torque, stall torque, braking torque, etc.
> ##  the prositel  numbers are not real.   If you look at any of these 
> rotators, the
> start up current in the motor is easily triple the running current.  Hence 
> the..
> start up torque numbers they quote  are much greater than the running
> torque number.   That high start up current only last 1-3 seconds when you 
> measure it.
> As noted, the upper and lower casings shoulda been welded
> together, instead of using 4 x  tiny machine screws.   They went cheap on the
> power xfmr.  It may well be an issue of using a 60 hz rated xfmr on 50 hz...
> which will surely cook it.
> ##  brake wedges  are steam engine technology.  The T2X is rated for
> 1000 in lbs =  83 ft lbs of torque.   1000 divided by 12 = 83.   83 ft lbs
> is  miniscule.   The ham-4-5   is even less, at  just 800 in lbs = 66 ft lbs.
> These are toy rotors at best.  Potentiometers  are passe these days. A buddy 
> has replaced
> several of the bournes pots in his protistel PST-61.
> ##  If you folks intend on turning a big array, at least try and torque 
> balance each
> ant in the array, with either a counterweight....And-OR  a torque compensation
> plate.  That is all explained on kurts  site.    I used his software to 
> design several of them
> with great success.    One fellow tested his hb 20m yagi  with and without 
> the TQ plate
> on a short tower, with NO rotor..and in a high wind.   With the TQ plate done 
> right, the yagi
> will NOT windmill in the wind.   With out the TQ plate, it will literally 
> bust the wedge brake
> and then rip the gears apart in his T2X.
> ##  The 83 ft lbs of TQ  pales in comparison to the 1250 ft lbs of TQ  from
> a small prop pitch  from k7nv.   The small prop pitch + mating GH box
> +  k7NV  super mast clamp is the ultimate solution.  GH makes  a special
> version of their box, made esp for the K7NV Prop pitch.  Kurt has
> modified the PP, so it uses digital pulses  from the magnets he installs.
> It uses a hammond xfmr inside the GH box..for the PP...and only outputs
> one dcv.
> ##  The mast clamp that K7LXC uses for the OR-2800  is for a 2 inch mast
> only.  The K7NV version is  for a  2 inch mast also...and he also makes a 3
> inch version and any other mast od you want to use, like 2.875 inch, etc.
> They work, because they are designed  for one OD of mast.   My 2 inch OD
> x  .375 inch thick chromolly mast just barely slides into the k7nv clamp
> assy.   You barely tighten the 5 x bolts, and it pinchs the mast so tight,
> it will never slip on you.
> ##  The GH box is slick, like having a 9 speed automatic transmission
> in a car.  Starts off slow, then ramps up to full speed... whizs  over to
> Europe, then starts the slowing down  ramp down.   You wouldn’t put
> your car into park..while driving  down main street, so  don’t do it on
> a  rotor either.
> ##  whatever size rotor you buy, go one size up, and don’t go cheap.
> If you destroy it, then you have to spend $$  to fix it, then spend even more
> $$$  to buy the bigger rotor to handle the job.  Or  expect  a repeat
> of the destruction on your rebuilt rotor.  Wind pressure goes up to the
> SQUARE of the  wind speed.   A 70 mph wind is DOUBLE the impact pressure
> of a 50 mph wind.   And a 83 mph wind gust  is  TRIPLE the pressure of a
> 50 mph wind.   Any gust only has to last just a few seconds to rip an
> under rated rotor apart.
> ##  You will  save  nothing buying a small rotor, trust me.
> Later..... Jim  VE7RF
> 73
> Roger (K8RI)
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