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Re: AO-7 for FD?



Hi Jon,

Sorry I didn't get to this last week - very hectic.

At 06:33 AM 6/25/2003 -0500, Jon Ogden wrote:
>Also, Frank,  the passband is just weird on AO-7.  The satellite seems to 
>have very little gain on either end of the passband.  By this I mean that 
>downlinked signals are VERY weak.  If you go to the middle, that seems to 
>be where the passband gain is.  But there's also a segment of that 
>passband that tends to put the bird into oscillation.  I'm not sure if 
>this is due to stations running too much power, etc.  But you'll want to 
>avoid it.  I can't remember the frequency range for that (and it's 6:30 AM 
>and I just woke up!), but it tends to be a few kcs above the mid-point of 
>the passband.  Most people stay right around the middle or just slightly below.

The linear transponder is definitely much higher gain in the middle of the 
passband for sure.  And the oscillation you are hearing is FMing when it is 
running out of power.  If really strong stations start pumping signal in, 
it tends to do that.  The trick is to reduce power as it approaches, and 
increase as it's leaving.  With no batteries (or even big capacitors) to 
control the voltage it's very easy for AO-7 to go undervoltage.  You can 
hear it happening, and you just need to remind people to reduce power.  I 
usually work it with 10 watts or less.

How did you make out?  I had a Murphy - intermittent break in coax that I 
couldn't fix in time.  Did manage to make one QSO on FO-29 and one on UO-14 
but I think they were a fluke.

-emily
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