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.
