[Milsurplus] DC-6A xtal holder

[Bob Camp]

Hi

Many of the common CMOS oscillator circuits will take off in an RC 
mode. When they do they wander all over the place. It's pretty 
noticeable either on a frequency counter or listening to it on a 
receiver.

Unless the crystal is the size of a dinner plate it's likely to be some 
kind of flexure bar cut. There will be all kinds of higher frequency 
modes present. Depending on how you clamp the bar you will make one 
mode dominant over the others.

Since you are trying to use the crystal as a filter rather than as a 
resonator in an oscillator some of the change won't be as important. 
However if you clamp it in a fashion that kills the 470 KHz resonance 
that will be a problem ...

	Enjoy!

		Bob Camp
		KB8TQ



On Nov 1, 2004, at 9:05 AM, Unserviceable but Repairable wrote:

> That's what holds the xtal-filter 'rock' in a BC-312/342.  We had
> a DC-8 discussion recently so this counts.  This isn't an octal-
> socket fella, it's a screw-tab package that looks like a xmt mica cap.
>
> My '312 had no xtal-filter action so I removed same.  Looks like 
> horrible
> job but, upon removal of a IF can, quite easy.
>
> Tried dang thing in a CMOS 4011 test osc. / 100kc calibrator.  Ran
> at 745kcs.
>
> Dissambled, cleaned, & re-tested.  Again 745kcs.  Began loosening two
> 'clamp screws' & thing changed modes to 470kcs.  Where it shud be.
>
> Screws real loose & I'm hesitant to re-assemble.
>
> Think rock 'X-Y cut' & 470 is mode down long axis & 745 up short one.
> But my last name ain't Bliley or Knights.
>
> Any shared experiences?
>
>   Thanks,
>
>      Marty
>
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