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Re: frequency jumps while listening to AO-40??

W3SZ R Rehr wrote:

> Hello, all!
> I am writing with a question about something I observed listening to AO-40
> today.  I was listening to the 2401 MHz downlink and periodically (perhaps
> every few minutes) my received signals (whether my own uplink, another
> station's downlink, or the MB) would shift erratically down in frequency by
> about 300 Hz, and then return to the original frequency.

<major snip>

I noticed the same thing.  I was in several QSOs between 1943z and 2100z, and then
dialed up the beacon and copied telemetry for a hour or so.  I did notice the same
thing during my conversations (especially the latter part of the period), and while
copying telemetry, the frequency shifts were even greater in frequency.  A number
of times, the beacon drifted right out of my receiver (no ability for AO40RCV to
control my radio).  I observed frequency changes of over 1 KHz.

Since my TSI downconverter is normally pretty stable, and the PCR-1000 receiver is
EXTREMELY stable, I was a bit perplexed.  I did think that maybe partial clouds
would sometimes block the sun resulting in the TSI alternately being heated and
then allowed to cool, but that was not the case as there was not a cloud in the
sky.  There was essentially no wind either that would account for temp changes in
the TSI.

Jim Walls - K6CCC
626-302-8515    FAX  626-302-7501
AMSAT member 32537 / WSWSS member 395

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