The extra 3 kHz or so is due to the buffer gas shift of the Rb hyperfine transition.
-RL ------------------------------------------------------------ Robert Lutwak, Senior Scientist Symmetricom - Technology Realization Center 34 Tozer Rd. Beverly, MA 01915 (978) 232-1461 Voice [EMAIL PROTECTED] (Business) (978) 927-4099 FAX [EMAIL PROTECTED] (Personal) (339) 927-7896 Mobile ----- Original Message ----- From: "Normand Martel" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, April 20, 2006 10:44 PM Subject: Re: [time-nuts] time-nuts Digest, Vol 21, Issue 22 > Help me! I need explanation! > > Robert Lutwak wrote: > >>With that said, the Perkin-Elmer rubidium on the IIR >>satellites is an outstanding clock, unquestionably > the >>best rubidium ever manufactured for any application, >>with short-term stability an order-of-magnitude > better >>than the IIF cesiums. The drift is also remarkably >>low for a rubidium oscillator, compared to commercial >>rubidium, and, with daily updates, they will >>outperform the cesiums, though the cesiums will beat >>them outside of a week or so. > > Well, i've got the PDF brochure for the Perkin-Elmer, > and it's indiscutably an outstandingly superb Rubidium > frequency standard (458 000 hours MTBF!!!), but > there's something that ticks me here, and i've seen it > on other rubidium standards. Let me explain: > > On the brochure, the output frequency is 13.40134393 > MHz and in the RF section of the block schematic, we > can see that the 13.40134393 MHz OCXO is multiplied > 510 times (classic x6 followed by an SRD x85) before > driving the physics. If my calculator is OK, that > gives me 6834685404.3 Hz. However, the hyperfine > transition of Rubidium is at 6834682612.8 Hz! A > difference of 2791.5 Hz (0.40843 PPM)!!!! I don't > understand! That's not a Lada, that's a "Ferrari" > grade standard! > > As i wrote earlier, i've seen a similar difference on > another (Efratom, if i remember) Rb standard! Can > someone explain me? I don't understand! > > Thanks for your attention! > > Normand Martel > Montreal, Canada > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.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
