[time-nuts] optically excite a quartz crystal?

Bob Camp lists at rtty.us
Mon Apr 21 09:16:51 EDT 2014


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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