[TowerTalk] OR-2800PX Point and Shoot?

[Jim Thomson]

Date: Thu, 03 Mar 2011 02:22:20 -0500
From: K8RI on TT <k8ri-on-towertalk at tm.net>
Subject: Re: [TowerTalk] OR-2800PX Point and Shoot?

Point and shoot?

73

Roger (K8RI)

## The GH  box's  have a large knob on the front panel....marked off over 360 degs.  
The digital display always shows the CURRENT  heading.    You simply crank the knob
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 speed..like 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 heading...like 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 that. 

##  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