[time-nuts] optically excite a quartz crystal?

REEVES Paul Paul.Reeves at uk.thalesgroup.com
Tue Apr 22 04:31:29 EDT 2014

I'll have to check (dig it out from under a pile of gear.....) but if I remember correctly the HRO receiver (at least the early, pre-war, ones) had a 'non-contact' crystal holder for the IF notch filter. The crystal was a block about 1/2" square and a bit less thick (-ish) and fitted loosely between two support plates which incorporated the electrodes. It was certainly not a tight fit and the crystal could be easily removed.

Paul Reeves        G8GJA

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Chuck Harris
Sent: 21 April 2014 14:01
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] optically excite a quartz crystal?

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

-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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