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Re: AO-10



At 06:38 AM 4/16/1999 -0500, you wrote:

>The notes on AO-10 say not to use the sat if the beacon is FMing. What does 
>FMing sound like?
>
>Keith

It's a shift in transponder output frequency caused by variations in
available/utilized voltage/power at the transponder.  In its current
condition, AO-10 is rotating very slowly, and probably wobbling some as
well.  If you go to an unused portion of the passband and send a CW signal
on the uplink, listen to your sideband tone on the downlink and you'll hear
it drift up and down over a minute or so....that's a form of FM'ing,
probably due to variable power from the solar panels caused by variations
in illumination, or maybe in the functional state of the very old panels.
Of course, if someone else loads the transponder with a heavy signal during
your experiment, you may hear a freq. shift then as well.  At times I've
heard high power CW signals elsewhere in the passband that I can copy by
listening to the frequency shift of the beacon tone!

The considerations about not utilizing AO-10 during FM'ing are more
theoretical than real.  Certainly, if you key a signal to the transponder
while listening to the beacon and you hear a marked drop/shift in the
beacon signal, then conditions are really marginal and you should wait for
improvement.  However, I would not let the relatively mild FM'ing now being
experienced as AO-10's illumination improves deter you from using it.  Have
fun. 


-- 
 ________________________________________________________________________ 
 Stacey E. Mills, W4SM    WWW: 	http://www.cstone.net/~w4sm/ham1.html 
   Charlottesville, VA	  PGP key:	http://www.cstone.net/~w4sm/key.asc    	
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