[Test-Equipment] Mesurements Corp Model 111-B question

[chearn]

Richard,
 From my fading memory, 32 PF was the industry-wide standard value of 
circuit shunt capacitance for crystals operating above the series 
resonance, somewhere below the crystal's natural parallel resonance.  
That is, the crystal reactance at the specified operating frequency was 
inductive.  Regards, Chase/K4AFW


On Sat, 16 Jul 2011 14:13:15 -0700, Richard Knoppow wrote:
> ----- Original Message -----
> From: "Glenn Little WB4UIV" <glennmaillist at bellsouth.net>
> To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>; "Discussion
> of Electronic Test Equipment"
> <test-equipment at mailman.qth.net>
> Sent: Saturday, July 16, 2011 1:38 PM
> Subject: Re: [Test-Equipment] Mesurements Corp Model 111-B
> question
>
>
>> Send a copy of the schematic to International Crystal.
>> They can determine the proper crystal from the circuitry.
>> If you determine the capacitance and get it wrong, it is
>> your problem.
>> They can eliminate the guess work.
>>
>>
>>
>> 73
>> Glenn
>> WB4UIV
>
>       I have a handbook for it, if I can find it, and could
> send the schematic. No handbooks exist at BAMA or other free
> sources.
>       I think the postage for a round trip for the whole box
> is more than the thing is worth.
>       I tried measuring the capacitance at the crystal
> terminals with a Boonton Q meter and with a Boonton RX
> meter. Neither gave me a meaningful reading. A replacement
> crystal I got from someone else is off frequency. It
> measures the same on the calibrator, a counter with a
> crystal tester, and on a Millen Grid Dip Meter, all the
> same. I also get on-frequency readings from the crystal
> tester on miscellaneous crystals including crystals for both
> a Collins R-388 and Drake R4xB which makes me think the 10
> mhz standard crystal is probably a 35pf (or is it 32pf)
> crystal.
>      This was a useful box when it worked. The trouble is
> definitely the crystal, it oscillates with other crystals.
>
>
> --
> Richard Knoppow
> Los Angeles
> WB6KBL
> dickburk at ix.netcom.com
>
>
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