The etching referred to was by post-war hams, -John
=============== > Hi > > Early in the WWII era, quartz blanks were not commonly etched after begin > ground / polished to frequency. This left debris on the surface of the > blank. The net result was that the resonators failed after a period of > time in the field, especially under damp conditions. The problem got so > bad that it actually threatened the ability to communicate in 1942. A > fairly high level team looked into the issue and etching of blanks (and a > few other mods) were made a mandatory part of all crystals suppled to the > government. Ammonium bi-flouride and water was the most common etchant in > that era. There are a number of papers about the whole deal in the FCS, > and many stories told by those who were part of the changes. > > Bob > > > On Apr 21, 2014, at 10:10 AM, J. Forster <[email protected]> wrote: > >> No. There is just a little rectangular quartz wafer. No plating. >> >> In fact, post WWII, when many ham transmitters were 'rock bound' (ie: >> crystal conteolled) it was common pratice to regrind mil surplus rystals >> to move them into the ham banda. >> >> Apparently, some were also etched using a cleanser called Whink, which >> contains a flourine compound. >> >> Also, some advocated applying graphite from a pencil lead was used to >> decrease the frequency. >> >> If the crystal ativity was low, they were taken appart and cleaned. >> >> >> >> -John >> >> ============== >> >> >> >> >>> 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.
