Hi If you find that your EFC port is low impedance - check it for a bias voltage. It may well have a pull up resistor to an internal Vref. The intent is that you simply tune it with a resistance to ground.
Bob > On Jan 6, 2015, at 8:49 PM, Daniel Mendes <dmend...@gmail.com> wrote: > > > I tried something like that once just to discover that the OCXO VFC port had > low impedance, so my voltage divider didn´t behave very well. So i put an amp > op in unitary gain configuration between the two and things improved a lot. > Then I changed the amp op for a DP precision part and things improved again. > Then I choose resistors/trim pot with low TCR for the voltage divider and > things improved again. Then I made a good layout, termally coupling the > resistors.... well, you see this has no end :) > > Daniel > > On 06/01/2015 22:40, ct1dmk wrote: >> Hi, >> >> With a multiturn pot and a 78L05 I can get a 0 to 5V EFC to tune >> an OCXO on desired freq. But... maybe other voltage regulators >> or other scheme have better temp stability than the old 78L05. >> >> Before I crawl lost in new'ish fancy regulator land does anybody >> know the killer solution/IC for this job ? >> >> Luis Cupido >> ct1dmk. >> >> >> _______________________________________________ >> 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. _______________________________________________ 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.
