Hi Bob, Do you think that maybe the oven current difference when the temperature changes could be at the root of this? To me, it seems like this started when I put the divider in. Before that, drift might have been hidden due to the lower resolution, I suppose. In any case, Mouser has my money now, and we'll see what happens when better quality resistors are put in.
BTW, I'm feeding the pull-up divider with +5V from a 7805C bolted to the case. I could switch that to the +6V VRef from the OCXO if you think that would make any difference. The case used to be an HP 37203A. >________________________________ > From: Bob Camp <[email protected]> >To: Discussion of precise time and frequency measurement <[email protected]> >Sent: Friday, January 31, 2014 3:50 PM >Subject: Re: [time-nuts] EFC divider resistors > > >Hi > >If you are going to attenuate the EFC *and* center it up around 3V you will >also need a voltage reference. Even a good one has a TC. You also have oven >current running in the ground pin which contributes to voltage issues (oven >and EFC share a common ground). Past that, you have thermocouple issues >(resistors, wires, OCXO pins are different materials) …. > >Bob > > _______________________________________________ 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.
