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Re: AO-40 AGC study,please read it!




>Has anybody identified the cause(s) of sudden drops in the AO40 downlink 
>signal strength?  I'm talking about when everything is working fine, and 
>then the signal SUDDENLY drops by ~10 dB for ~30 seconds, and then 
>SUDDENLY returns to "normal".  The duration of the drop is longer than a 
>typical LEILA attack, and I can't hear a LEILA siren when I tune up and 
>down a few kHz.
>
>What do you guys with panoramic receivers see in the passband when 
>everything suddenly drops 10 dB?  Has anybody noticed a geographic pattern 
>when this occurs and doesn't occur?  I suppose this could be caused by an 
>extremely powerful SSTV or RTTY station.  Or perhaps the offending signal 
>is NOT a ham?

Wayne, I've notice the same thing  on AO40, asked about it here a while 
back, and got
no answers except AGC "ta da ta da"......

I've watched the passband with an ICOM PCR 1000 at the same time, and have 
observed no
LEILA either, and she is very obvious...The only  other thing is some SSTV that
is quite strong, and LEILA was not tripped....Unless it happens to be a lot of
simultaneous SSTV, and it seems to me that would indeed be a rarity..

Along the same note, I DO NOT UNDERSTAND why SSTV signal strength has to be 
that high,
I've done SSTV on both O13 and 40, and use no more power than I do on cw???

Anyone have answers??


            73, Dave wb6llo@amsat.org
                    Disagree: I learn....

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