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[TowerTalk] OR-2800PX Point and Shoot?

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Subject: [TowerTalk] OR-2800PX Point and Shoot?
From: "Jim Thomson" <>
Date: Thu, 3 Mar 2011 00:19:34 -0800
List-post: <">>
Date: Thu, 03 Mar 2011 02:22:20 -0500
From: K8RI on TT <>
Subject: Re: [TowerTalk] OR-2800PX Point and Shoot?

Point and shoot?


Roger (K8RI)

## 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. 

later....... Jim   VE7RF


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