From: "Dave Brown" <[EMAIL PROTECTED]> Subject: Re: [time-nuts] How Rubidiums make their frequency Date: Thu, 20 Apr 2006 09:13:08 +1200 Message-ID: <[EMAIL PROTECTED]>
> > ----- Original Message ----- > From: "Matt Ettus" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]>; "Discussion of precise time and frequency > measurement" <time-nuts@febo.com> > Sent: Thursday, April 20, 2006 7:55 AM > Subject: Re: [time-nuts] How Rubidiums make their frequency > > > > Since we can now make DDS's with arbitrary frequency resolution, > > could > > you make an Rb oscillator without the magnetic field adjustment? > > snip--- > > I suspect the FEI 5650 series does just that- a 50.255+ MHz VCXO is > 'locked' at 1/136 of the 6.8GHz Rb resonance and there is no 'user' > adjustment provided for the physics package. I suspect the magnetic > field IS preset in the factory but thereafter intended to be left well > alone. Well, first of all they state that it is 1/136 and yes it is preset put available as a controlable thing as an option. See their sales-material and you find it (I did): http://www.freqelec.com/ > The 50.255+ VCXO drives an AD9830-all fine tuning of the output > frequency takes place by setting the DDS. > Can anyone comment further on this? > > On a related issue- the physics package in these units draws a > significant current at startup- I'm considering current limiting the > suppy until the current drops back to a lower value-I guess this > delays the warmup somewhat but it would reduce the current required > from the supply to the steady state value, for example, thus allowing > a smaller power supply rating. I would not do that. However, the heater supply isn't as critical so it would allow itself for a very simple supply anyway. Cheers, Magnus _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
