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Re: AIDC down-converter drift



Phil,

Even if you change the crystal from 8.8984 to 8.8125 MHz (145 MHz IF), the
multiplication factor will still be 256. This small change in reference
frequency will probably reduce the drift by less than 1%. I think a heater
and pipe insulation arround the DC work best.73

Pieter

----- Original Message -----
Wrom: HJEXXIMQZUIVOTQNQEMSFDULHPQQWO
To: <amsat-bb@AMSAT.Org>
Sent: Monday, September 01, 2003 8:54 PM
Subject: [amsat-bb] AIDC down-converter drift


> 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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