[time-nuts] Firmware and antenna for Stanford Research FS700

[Charles Steinmetz]

Dave wrote:

>1) Do you have any suggestions for a replacement for the LM394CN, which is
>obsolete and unobtainable from any reputable source? There are plenty on
>eBay for a few $'s from China, but the probability of them being fakes is
>greater than 0.99. The MAT12 seems to be one possible candidate for a
>replacement and while not cheap, is available from reputable sources like
>Farnell.

The MAT12 should certainly work, but there is *plenty* of DC 
degeneration in the circuit (1v at each emitter), so there is no 
advantage to matched transistors.  A pair of Zetex (Diodes, Inc.) 
ZTX849 or FZT849 actually have significantly lower voltage noise than 
either the LM394 or MAT12.

Best regards,

Charles