Brooke, I believe he is referring to the Efratom FRS-C Rb oscillator which was very popular in telecom applications. I looked at the specs for one on eBay (140128295361) and in my FRS-C manual and came up with:
FRS-C Electrical Specifications: Long-term Drift: < or = to 5x10-11/mo*, < or = 5x10-10/first year, < or = to 2x10-10/year thereafter. Trim Range: +/- 2x10-9 max. The electrical tuning description in my manual lists the adjustment range as +/- 1e-9 to +/- 1.5e-9. He states "the manufacturer provides a C-field adjustment range equivalent to +1.5E-9" which is similar to the tuning description in my manual, and he states "The aging rate of the standard is specified as 2E-10/year" which is the same as the long-term drift spec listed on the eBay unit. So my entry in the "Name That Rb Frequency Standard" contest is the Efratom FRS-C. When will the winners be notified and what prizes are offered? BTW, the 7.5 year life due to limited C-field range is well beyond the typical Rb lamp life I have experienced with these units, which has been more like 3-5 years of continuous operation with a new lamp and a heavy duty heat sink on the unit. A few units I have worked with did somewhat better than this, but I personally haven't come across an FRS-C yet where the C-field range couldn't put the unit on frequency if everything else was working properly. Having Fun! Richard > Hi: > > Came across US patent 4,899,117 "High Accuracy Frequency Standard and Clock > Sytem" by John Vig, Feb. 6, 1990. > http://www.google.com/patents?id=068BAAAAEBAJ&dq=4899117 > > In the background section he says: > > "For example, in one of the most popular Rubidium frequency standards on the > market, the manufacturer provides a C-field adjustment range equivalent to > +1.5E-9. The aging rate of the standard is specified as 2E-10/year. > Consequently, at the specified aging rate, the limited C-field adjustment > range > limits the useful life of this Rubidium frequency standard to 1.5E-9/2E-10 or > 7.5 years." > > Which standard is he reffering to? > > -- > Have Fun, > > Brooke Clarke > http://www.PRC68.com > http://www.precisionclock.com > > > _______________________________________________ > time-nuts mailing list > [email protected] > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
