RE: [amsat-bb] AO-40 Success! Desense problem solved - First QSO - Thank you!

["Howard Long" <howard@xxxxxxxxxxxxxx>]

Hello Mike

> However,
> IT said that doppler was about +10000khz but I found the beacon at about
> .319 instead of .333. I had some trouble keeping on signal high in the
band.
> I could transmit, find myself and tune the voice in. But if I shifted the
> receiever frequency again (which caused the TX to change too), it took
> additional fiddling my receiver to find myself once again. There just
seemed
> to be a non-consistent offset in the up/down link frequencies of my
doppler
> tuning. Hmmmm.

o From switch on to being warmed up, the AIDC units shift several kHz - this
can take a while.

o Even gusts of wind and other scenarios which alter the unit's temperature
will change the LO.

o Of course, you're also using a first cut beta copy of that InsantTune hack
I did for the XIT on the FT-817 ... ;-)

o Even the spacecraft's frequency accuracy changes by at least 1kHz,
although this is largely insignificant in my experience compared to the
AIDC's accuracy.

The reality is that everyone does a little twiddling. Generally when setting
up portable I put power right onto the downconverter as the first job I do
in an attempt to get some stability. That way, by the time I'm ready, things
will have settled down somewhat.

73, Howard G6LVB


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