[amsat-bb] AIDC down-converter drift

[Phil <phil@xxxxxxxxxxxxxxxx>]

Hello All,

I have an unconverted AIDC 3731AA down-converter that seems to never stop 
drifting no matter how long it is left powered up. After a contact this 
morning with Dominic, from Italy, I now realise that there is an advantage in 
raising the IF to 145 MHz due to a lower multiplication factor of the crystal 
oscillator. Something that I hadn't considered previously.

I'd like to eliminate, or at least reduce, this drift. My question is, what 
are the specs for the crystal that I should order? I imagine that all I have 
to do is replace the crystal and that no tuning is required. Is that correct? 
My test equipment is very basic.

The question of drift has been dealt with before by list members and I see 
that people are using pipe insulation over their down-converters and crystal 
heaters. The difference between night and day temperatures here is no more 
than 15 degrees Centigrade. Even so, maybe I should try the insulation first 
before going any further?

-- 
Regards,
Phil.


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