Hi One of the reasons for going to plated electrodes was to control the damping on the resonator. You control plating thickness fairly tightly for this reason. A great big lump of iron on your vibrating area does indeed damp it.
Bob On Apr 21, 2014, at 9:29 AM, Mike Feher <[email protected]> wrote: > 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: [email protected] [mailto:[email protected]] 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 <[email protected]> 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 >> _______________________________________________ >> time-nuts mailing list -- [email protected] To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
