Someone asked what the Time-Nuts way of calibrating a Rb source would be. I'm no expert, but here's my 2c worth:
I don't like making adjustments, as they can lead to lowered reliability, lowered understanding of the processes of ageing, and are also more work. As someone else pointed out, provided you know where your oscillator is, it is stability that is important, not accuracy, so to me, calibration is a matter of MEASUREMENT AND DOCUMENTATION, not twiddling of knobs. I keep records of all my oscillators, without adjusting any, and so have a very clear idea of their ageing rate, and can thus predict with confidence where they will be without necessarily measuring on a daily basis. For example, I know my Morion MV89 is currently at 10.000000271MHz, going up at 2.6e-10/day, and my HP E1938A is at 9.999998082MHz, going down at 8.7e-10/day. As a reference I use a Samsung GCRU-D GPS Discplined Reference, and make measurements with a Pendulum CNT-90 counter. I borrow the counter from work when I need it, as my own HP 5315A counter lacks the resolution. As a matter of interest, the OCXO in the Samsung (which is a C-MAC STP2145A) has been under my eagle eye for two years now, and has an estimated rate of -2e-9/year, incredibly low, but probably just dumb luck. Because it is GPS locked, this is estimated from the going rate of the EFC voltage and the known Kvco of the OCXO. Regards, Murray ZL1BPU _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
