Hi Well I can name at least one post war ham (me at age 14) who did not understand the need for etch after grinding…
Bob On Apr 21, 2014, at 11:21 AM, J. Forster <[email protected]> wrote: > 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. _______________________________________________ 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.
