Alfaspid Rotators http://alfaspid.ca
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<K8RI-on-TowerTalk@tm.net>
> 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
> ### 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
> ## 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,
> 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,
> 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
> 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
> Roger (K8RI)
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