On 11/3/2012 3:37 AM, Jim Thomson wrote:
Date: Fri, 2 Nov 2012 14:41:07 -0400
From: <w8hw@att.net>
To: <amps@contesting.com>
Cc: w8hw@att.net
Subject: [Amps] NEW Tail Twister Rotator
If interested.
NEW Tail Twister Rotator still in original box. Includes Contains (All new in box),
New control head, New hardware, New connectors, manual New Warranty Registration
card. I purchased one two many units for what I needed.
http://www.ebay.com/itm/330810645370?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
Contact me direct and ask me me to pay the shipping. w8hw@att.net Save three
ways, $200.00 plus TAX plus SHIPPING on brand new unit. This won?t last long.
Tail Twister Rotator is Hy-Gain big rotator. Turning power 1,000 pounds.
73, Bruce, W8HW
### BTW, the “turning power” is NOT 1000 lbs on that rotor. It’s rated at 1000 INCH
lbs of....”stall torque”. 1000 inch lbs / 12 = 83.33 FOOT lbs of stall torque. I find it
amusing how these rotor makers like to bs the numbers
on these rinky dink rotors. They will use terms like.. “start up torque..... running torque...and
stall torque” . The start up current on any of those small motors is typ triple the running
current...... hence the “start up torque” number can be a LOT higher than the
actual running torque. Stall torque is just that, you put enough of a load on
it, that it actually stalls out....as in ZERO rpm for both the motor and
obviously the ant itself.
### In the bigger scheme of things, 83 ft lbs of torque is not much at all.
On a 36" pipe wrench it is slightly less than 28# (83/3), or you could
hold it easily with one hand. OTOH a 24" wrench 83/24= 41#. It might
catch you unaware, or unprepared, but again it can be held easily.
The motor is tiny and it takes very little input from the output shaft
to drive the motor armature and with the gearing that little sucker
really screams as you are looking at a gear ration of nearly 2000:1.
I've never checked but the armature probably turns some where between a
1000 and 1700 RPM. That's why they need that wedge brake.
With one of the double worm gear rotator it's possible to have several
thousand foot in# or in the case of the PST61DHP 7,641/12 or 641 ft #.
or 1377 ft lb of break/holding torque. The case might not be up to it,
but that is a lot of torque.
Don't go experimenting though as you need things anchored securely and
it's very easy to severely pinch things you'd prefer not to pinch.
73
Roger (K8RI)
The flip side is.... IF ant makers torque balanced their ants
correctly, you would require very little TQ to rotate the array. I
used K7NV’s software to design a TQ compensation
plate on a local fellow’s HB 5 el 20m yagi. Without the TQ comp plate
installed, it would literally destroy the tail twister...plus a 2nd tail twister.
He had taken a 204BA......and had added a 5th ele to it....plus lengthened the boom.
He had
mounted the yagi at it’s center of gravity, which then put a lot more boom out
one side vs the other. That alone created the gross TQ imbalance.
## The fix is simple, either mount at the dead center of the boom and use a counterweight at the
light end of the boom. (K7NV’s software will also calculate the required weight.) Or
mount at the CG... and use the TQ comp plate. You can also use a combo of both schemes. The
alternative is to use a rotor that has WAY more TQ. The tq comp plate scheme was tested by
installing the yagi on a short 30’ tower, with NO rotor..and just let it windmill. In a
30-40 mph wind it did not windmill...and in fact the owner could climb up the tower and turn the
yagi by hand. It stayed put in whatever direction it was pointed. The comp plate was then
removed, and the yagi will windmill badly. If stacking yagi’s on one mast, alternate sides
on the mast to account for the
offset between mast and boom.
## IMO, for the $$ they want for the tailtwister, it really is not a big bang
for the buck.... and ditto with the Ham-3-4-5 series with its 800 in lbs of tq.
( 67 ft lbs). Rating any of these rotors in terms of ant sq footage is
ludicrous.
Jim VE7RF
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