> eBay item 150082419799 (Genrad 475-C)--is this some kind of OCXO frequency > reference? From the description, it sounds like it might be used to > monitor a broadcast transmitter frequency. Be sure and scroll down and > check out the wood and foam oven box and the "quartz plate" resonator. > > The '56 GR catalog at the bama site doesn't show a 475-C, but that's not > surprising as the 475-C looks quite a bit older.
Yes, that's a nice example of a mercury thermometer regulated, ovenized quartz plate oscillator, complete with balsa wood case and lots of asbestos (not foam) insulation. I have a couple of these ovens -- though with 100 kc xtals, not the special broadcast freq. spkr_volume -- please send me email, OK? For other old GR oscillator stuff see: http://www.leapsecond.com/museum/gr1103a/ http://www.leapsecond.com/museum/gr1190a/ http://www.leapsecond.com/museum/gr676b-50kc/ http://www.leapsecond.com/pages/old-genrad/ Of special note, see the 4 patents I have there on the web page, like this one: http://www.leapsecond.com/museum/gr676b-50kc/US1967185.pdf Would you believe that GR had double ovens all figured out back in 1931? HP wasn't the first... /tvb _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
