[time-nuts] optically excite a quartz crystal?

Mike Feher mfeher at eozinc.com
Mon Apr 21 09:29:25 EDT 2014


Agree there are some like that, but, only a few. A large spring loaded plate
is not going to dampen a piece of quartz vibrating in the MHz range at all.
Granted, the sealed, and metalized construction is a better one, but it is
mostly done to minimize shock and impurities. - Mike 

Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Bob Camp
Sent: Monday, April 21, 2014 9:17 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] optically excite a quartz crystal?

Hi

If you look closely at most of them, the plates are not flat. They are
higher on the edges than in the center. There's a gap in the middle. If you
don't have the gap, the blank is constrained by the big heavy plate. That
damps the resonance and lowers the Q.

Bob

On Apr 21, 2014, at 9:00 AM, Chuck Harris <cfharris at erols.com> wrote:

> I'm puzzling over this statement.  The FT-243's I have seen have a 
> spring that squishes the quartz blank between the electrodes.  They 
> aren't plated onto the quartz, but they are still in intimate 
> mechanical and electrical contact.
> 
> -Chuck Harris
> 
> Bob Camp wrote:
>> Hi
>> 
>> The WWII era FT-243 is one example of a crystal that has the active 
>> portion of the electrodes separated from the resonator by an air gap. 
>> There are lots of similar holders from that era that do pretty much 
>> the same thing. Non-contacting electrodes are not very new.
>> 
>> Bob
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