Date: Thu, 03 Mar 2011 02:22:20 -0500
From: K8RI on TT <k8ri-on-towertalk@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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|