There must have been several different versions of this unit. The oscillator I have is 5 MHz. The frequency dividers in the rack I got it out of were discrete transistor construction. Seems to me the clock used a 25L6 although I don't remember how they derived the heater voltage. There was also a phase locked frequency multiplier with outputs at 10 MHz, 100 MHz and 1 GHz. The frequency divider module had outputs down to 1 PPS.
After typing that I'm not sure the oscillator frequency is right. Maybe it's 1 MHz. I'm sure it's not 100 kHz. Regards. Max. K 4 O D S. Email: [EMAIL PROTECTED] Transistor site http://www.funwithtransistors.net Vacuum tube site: http://www.funwithtubes.net Music site: http://www.maxsmusicplace.com To subscribe to the fun with tubes group send an email to, [EMAIL PROTECTED] ----- Original Message ----- From: "phil" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> Sent: Friday, August 22, 2008 10:15 PM Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard > > ----- Original Message ----- > From: "Magnus Danielson" <[EMAIL PROTECTED]> > To: "Discussion of precise time and frequency measurement" > <time-nuts@febo.com> > Sent: Friday, August 22, 2008 5:25 PM > Subject: Re: [time-nuts] Restoring GR 1120-AB Frequency Standard > > >> phil wrote: >>> Gentlemen, >>> Original poster is trying to "RESTORE" this entire old General Radio >>> Standard ( a rack of equipment) to it's "original" glory. >>> He simply needs a part, a unique thermoswitch or a way to fix it, not >>> retrofit an atomic engine! This is a museum class instrument, 100kc. >>> >>> May I suggest start a new thread on the better/best merits/design of >>> temperature control. >>> Makes it rather difficult to follow a thread as the subject has changed. >> >> My proposal to use capacitive sensing rather than conductive sensing >> would handle the electrode oxide issue. It is meant as a means to go >> around the sensing issue with parts at hand and only some new electronic >> design of very simple form, not the means to supercalibrate something. >> >> I guess this only shows that time-nuts are time-nuts... >> >> Cheers, >> Magnus > > > Magnus, > Perhaps this will help understand why I made that comment. > > That old "primary" standard was quite a contraption. This things heyday > was > in the order of 1950's and used up into the 60's and some models into > early > 70's. Of course it was all tube equipment. > > My unit model was possibly a 620, it predated what Russ has (1100) but was > quite similar in design. Russ's unit has all the multivibrators in one > housing where mine was each separate. I think his is a 100kc oscillator > and > mine was 50kc. > > As I remember the one I had was in two 7-foot racks, a standard side and > frequency measuring side. My oscillator was 50KC though about 300 dollars > in > the mid 6o's would have bought a 100kc quartz bar to upgrade it > > The unit had each module or circuit in a separate 19" rack space all > averaging 8 inch high The main components, a power supply, oscillator > (about > 20 plus rack inches high by itself), separate multivibrators of 100kc, > 10kc, > 1kc, and 100 cycles. Yes they were called multivibrators though all tube. > It > also had a syncronometer at the top of the rack, better known as a clock. > Apparently the crystal was rich in harmonics and they made use of it in > this > assembly. That clock ran off of the 1 kc output. > > The heart of the oscillator, main part of this contraption used a quartz > bar > about 3/8 of an inch square and about 2 inches long suspended on 4 > springs. > If I recall it was a single oven but it's specs called for about > .01-degree > regulation. > > I don't remember all the fine details, but it had many other components > (all > seperate rack units), a separate 5kc interpolation oscillator, amplifier, > and even an 8-inch speaker to zero beat the standard to another unit, > talking about phase lock! > > So as you can see, these vintage units only use/value is that of an > antique > or conversation piece. A 10811 would blow it away performance wise. > > Now with an understanding of that old antique, that discussion was like > putting an electronic ignition in place of the old Ford Model T spark > coil. > You could, but .. You just search for the part. > > So it's not a "time-nut" issue as such other than appreciating the history > or the evolution of time. I can see from the varied posts this is one heck > of a super talented group. I guess we all get involved in something > interesting and easily get carried away, as in the discussion. Granted you > can do a given task many ways, and bantering ideas around is how things > are > born and perfected. Only problem is, it doesn't locate an "original" > antique > part, what he stated he wanted! > > That old GR stuff does occasionally show up, most free to haul off it's so > massive. A bunch of the old vintage GR standard parts was listed as a lot > on > ebay some months ago. > > Someone asked what happened to my old GR stuff. I disposed of over 100 > tons > of old electronics that had accumulated including this old GR stuff. One > of > my sidelines was the used equipment business and the sales of tube stuff > died. I had some 15,000 feet of "junk" as I call all this stuff. > > By the way, according to Bruce, that design of the old "thermoswitch" > achieved resolutions as fine as .001 degrees. > > It would be hard to build any electronic sensor of any design that is that > reliable and repeatable (.001 degree) with a "one-time" factory > calibration > good for a life exceeding 50 years without using a similar sensor design. > The unit in question with the electrode in mercury design lasted about 50 > years before showing it's age and misbehaving. > > Phil > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.