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Subject: [TowerTalk] (no subject)
From: "Zivney, Terry L." <>
Date: Thu, 3 Mar 2011 10:21:15 -0500
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Jim   VE7RF, wrote:

## The GH  box's  have a large knob on the front panel....marked off over 360
The digital display always shows the CURRENT  heading.    You simply crank the
over from say ZL land  to  say EU  [ 30 deg from me].... and sit back and watch
the show.
After a brief pause, the rotor will ramp up in a 9 x speed auto
transmission, and once up
to max speed..whizzes  over the pole to EU.   When it gets  20-30 degs  b4 EU..
it starts the slow down sequence
and ramps  down  from speed's 9, down to 8-7-6-5-4  etc... till  it's  barely
crawling along..then stops..exactly at
30.0 degrees.    It will put it within .1 deg  of where u want it every time.

##  once u start cranking the knob, the display will also display the  new
heading, or where ever the knob is cranked to.
That way you can dial up a specific 34.6 degs  if you like.
It's  all automatic, no fuss, no muss,  and with the
ramp up/down... you don't trash gears etc.   On ramp up, ur not slamming all
the torque on at once.  With the PWM
motor controller,  it ensure u get max torque, even when rotating at slow
speeds. PWM  just applies  max  normal
voltage.. but with gaps  between pulses.   IE:  they alter the duty cycle to
control the speed.   Since each pulse gets max voltage,
that scheme  minimizes any loss of torque.    IE; if u just reduce the
operating voltage to slow down a dc motor, sure it will run slower,
but the torque will also  drop off really fast.    The PWM scheme gets  around

##  Not having ramp up/down capability is a real detriment to rotor life.  It
makes me cringe when u see a heavy array, that has been
turning at 1 rpm  for 30 secs..then comes to a crashing halt..yikes.  Sorta
like driving down the highway at 60 mph,....then shifting into park.

The standard M2  Orion box has ramp up/ramp down features and variable speed 
PWM, too.
It just  doesn't ramp down in the default (Mode 1) manual mode, because if you 
want it
to STOP because of a problem, you don't want to wait for the power to STOP.  
The inertia of the
antenna will keep the motor turning anyway, if it's a large antenna.

Also, the stock GH box does not do prop pitch - doesn't have the power supply 

I like knobs -they belong on radios where I need continual access to  varying 
Digital input / control techniques like keypads, keyboard, and mice seem 
appropriate for
relatively set-and-forget operations, like turning my prop-pitch rotor.

Terry Zivney, N4TZ/9


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