Hi You can either do the math … yuck …. or just try it. It turns out that with a “normal” sort of EFC sensitivity (< 1 ppm / V) on a “normal” frequency OCXO ( <30 MHz) , the voltage can have a bit of noise on it and the phase noise of the device will not suffer. Simply put - you can run it with a 78L05 and the phase noise will be the same as with a short.
Since the phase modulation rolls off as 1/F for a flat noise spectrum, the noise on the EFC “chases” the phase noise floor as frequency increases. Toss in an internal bypass on the EFC line and it goes down even faster. If you get into OCXO’s that are more like VCO’s then things aren’t quite so easy…. Now, this is just talking about phase noise. If you look at stability, indeed a finite delta V on the EFC will change the frequency of the OCXO. Generally, the biggest factor is the voltage drop from the oven current getting into the EFC “loop”. Its actually pretty hard to keep them separate. Unless you can split them apart, they will limit your heroic efforts on EFC stability. Our 1 ppm / V OCXO above moves 1 ppb / 1 mv. If you are after a ppt, you need 1 uV of EFC “ground isolation”. Bob > On Mar 20, 2018, at 10:24 PM, Perry Sandeen via time-nuts > <time-nuts@febo.com> wrote: > > Yo Dudes, > Should one consider retrofitting HP 105's, Austron 1250's or HP 10811 power > supplies with the LT3042 for better performance? The price is modest. The > HP 10811 suggested PS for the EFC is a 723 circuit that spedc's 6 microvolts > ripple IIRC. > Regards, > Perrier > _______________________________________________ > 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.
