[sdiy] Black Magic oscillator cans

[Tim Ressel]

John & all,

The 'pullability' of regular crystals is usually +/-
50 to 100 ppm. If you need more range there are
special crystals with more range. But I think +/- 250
ppm is about the max. More than that and you're
talking varactor-tuned oscillators.

--tr


--- John L Marshall <john.l.marshall at gte.net> wrote:
> According to the ARRL handbook crystals can be tuned
> with a variable
> capacitor over a range of 50kHz to 200kHz.
> 
> Take care,
> John
>
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> 
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> 
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> 
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>
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> 
> ----- Original Message ----- 
> From: "Glen" <mclilith at charter.net>
> To: "John L Marshall" <john.l.marshall at gte.net>;
> "Synth-Diy"
> <synth-diy at dropmix.xs4all.nl>
> Sent: Sunday, July 20, 2003 1:18 PM
> Subject: Re: [sdiy] Black Magic oscillator cans
> 
> 
> > At 02:43 PM 7/20/03 , John L Marshall wrote:
> > >Crystals can be trimmed to an exact frequency
> with a small variable
> > >capacitor, either in series or parallel.
> >
> > I'm aware of that, but the tuning range is fairly
> limited. The amount of
> > tuning range is also affected by the oscillator
> circuit design, as well as
> > the crystal itself. Some circuits and crystals are
> more "tunable" than
> others.
> >
> > Do you happen to know if a "typical" 2 MHz crystal
> oscillator could be
> > tuned this way to a frequency of 2.00024 MHz? I
> don't have much "hands-on"
> > experience with the limits of a crystal's tuning
> range.
> >
> >
> > later,
> > Glen Berry
> 


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