The Datron 1081/1082 are 7-1/2 digit meters. The zeners are two pair of two zeners in series to get the ref voltage up high enough. In the two 1081s I had, they worked quite well, ref’d to the two Fluke 732As I had at the time. But not 8-1/2 digit grade, I don’t think. I have no idea what the 127x/128x sereis use; probably the LTZ1000A...

I believe the 1281 uses the LTZ1000. The datasheet mentions dual references. My 4920 has both a ltz1000 and a lm399. I think you can find pics of the 1281 dual ref setup on eevblog. I would not be surprised if the 8508a has a similar configuration. Todd On Saturday, December 20, 2014, Richard Moore <richiem5683@gmail.com> wrote: > > The Datron 1081/1082 are 7-1/2 digit meters. The zeners are two pair of > two zeners in series to get the ref voltage up high enough. In the two > 1081s I had, they worked quite well, ref’d to the two Fluke 732As I had at > the time. But not 8-1/2 digit grade, I don’t think. I have no idea what the > 127x/128x sereis use; probably the LTZ1000A... > _______________________________________________ > volt-nuts mailing list -- volt-nuts@febo.com <javascript:;> > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. >