li...@rtty.us said: > A 7805 has a *rated* temperature coefficient of 2 mv / C. Most parts do way > better than this. The problem is knowing if you have a good part or not. On > a 5V part, your reference could be running 400 ppm/C. Since the divider has > no impact on this number, it over-rides what ever you do with the divider > resistors. A good voltage reference will set you back about $50 or so.
Plan B would be to keep the 7805 at a constant temperature. > You commonly see a couple of mv of variation in the ground pin voltage with > oven current depending on exactly where the pin is terminated. Any change in > the ground setup can be an issue on an OCXO with the EFC in common with the > oven (which is most parts). Again, plan B would be to keep the OCXO at a constant temperature so the heater current is (close) to constant and the offset on the ground pin due to heater current would be constant. --------- I've heard comments about offset due to a single ground pin for several/many years, so it's nothing new. Why are manufacturers not providing separate pins? Are there OCXOs (that I haven't noticed) with 2 ground pins? Is the problem backward compatibility? In that case, I'd expect there would be a pinout with a new second-ground pin that offered an interesting "beat-this" challenge to other vendors. -- These are my opinions. I hate spam. _______________________________________________ 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.