With most of these old circuits reducing the LF noise contribution to the emitter/collector current by the biasing circuit by utilising lower noise power supplies and/or using improved biasing methods can improve the clse in PN significantly. The PZT3904 and PZT3906 are still available. Bruce
On Wednesday, 30 March 2016 1:00 PM, Bob Camp <kb...@n1k.org> wrote: Hi There were (and maybe still are) SOT-89 versions of the 2N3804 and 3906. They will handle more power than most of the other versions. That gives you better Vce on the string. They also have less package inductance which helps tie the base to ground. If you are building some of those circuits, they are worth looking for. Bob > On Mar 29, 2016, at 6:47 AM, Charles Steinmetz <csteinm...@yandex.com> wrote: > > See below for schematics of the NIST isolation amplifiers from 1990 and 1997. > NIST reported the isolation as >120dB. > > I built isolation amplifiers similar to these (with lower-noise power > supplies and biasing tinkered slightly for better dynamic range), and with > careful construction achieved isolation substantially better than 120dB (see > my post of 11/25/14 for more details). > > Best regards, > > Charles > <NIST_120dB_isolation_amplifier_schematic_email.gif><Iso_amp_NIST_schematic_with_values_5MHz_1997_email.gif>_______________________________________________ > 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.