Since the topic has been raised- herewith a few pix of an equally old (well, nearly!) OCXO using mercury-in-glass high and low set point thermometers for temperature control. http://homepages.ihug.co.nz/~tractorb/oven/ This came out of an early openwire carrier system-of UK origin-probably immediately post WW2 manufacture. One of the original glass xtals has been replaced with a much less interesting style holder.
DaveB, NZ ----- Original Message ----- From: "Tom Van Baak (mobile)" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Thursday, January 25, 2007 7:31 PM Subject: Re: [time-nuts] Nifty old GR OCXO? >> 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 > time-nuts@febo.com > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > > -- > No virus found in this incoming message. > Checked by AVG Free Edition. > Version: 7.5.432 / Virus Database: 268.17.8/649 - Release Date: > 23/01/2007 20:40 > _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts