On Nov 30, 2008, at 3:39 PM, tBruce wrote: > Message: 6 > Date: Mon, 01 Dec 2008 11:53:32 +1300 > From: Bruce Griffiths <[EMAIL PROTECTED]> > Subject: Re: [time-nuts] V refs > > The uA714 is claimed to be an OP07 equivalent. > A chopper stabilised amplifier would have lower drift and flicker > noise, > however the zener drift and flicker noise probably dominates. > > Stacking LTZ1000's in the same way is a little tricky. > The only satisfactory method I have devised so far uses a PJFET as a > voltage controlled resistor to sink the zener current whilst > allowing it > to be reused to bias lower LTZ1000s in the series stack. > > Bruce
Bruce, The 714 opamp provides gain in the Datron 1082, and I would use one LTZ1000 (or two in parallel, rather than try to use them in series). A while back I tried using two LM399s in series in a Fluke 895, and really didn't like the results -- a single 399 with an amp was better in every way I could measure. As an alternative to a chopper like the 1151, I might consider an OPA27. I have used the now unobtainable OPA111 in the past, and that was a superb DC amp; they (TI) claim the OPA27 is as good. Dick Moore _______________________________________________ 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.
