I guess, this is the so-called "Essen ring" crystal Regards Bernd -----Ursprüngliche Nachricht----- Von: time-nuts [mailto:[email protected]] Im Auftrag von Bruce Griffiths Gesendet: Sonntag, 1. März 2020 02:33 An: Discussion of precise time and frequency measurement <[email protected]> Betreff: Re: [time-nuts] What is the BEST crystal?
Interferogram showing vibration nodes etc for quartz ring resonator frequency standard attached. Bruce > On 01 March 2020 at 14:27 Bob kb8tq <[email protected]> wrote: > > > Hi > > It’s also the size of the 2.5 MHz 5th’s and similar parts made “way > back”. They went into glass packages the size of door knobs. Packaging / > design / mounting / processing has changed a lot since then. > > Bob > > > On Feb 29, 2020, at 7:41 PM, John Moran, Scawby Design > > <[email protected]> wrote: > > > > Wow, that provoked an interesting discussion! > > > > Thanks for all the information and references to further information - it > > should keep me quiet for a while. > > > > Interestingly 50mm diameter was about the diameter of the crystals used by > > the British Post Office in the early days for generating a master > > oscillator. It wasn't ground into a plano-convex lens but as a ring and was > > about 10mm thick. Like the old WW2 crystals the electrodes weren't plated > > but just contact rings. I have no idea what frequency they were ... by the > > time that I realised they were scrapping all this kit it was gone and I > > only managed to salvage two GPO Type 36 master 1S pendulums from a dumpster! > > > > Thanks again for all the feedback. > > > > John > > _______________________________________________ > > time-nuts mailing list -- [email protected] To unsubscribe, > > go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go > to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
