[volt-nuts] Fluke 732B

[Steve]

Frank,

Have you got a link to the eevblog Datron 4910 reference element decryption? I have a 4910 and am curious to see what they found, but am not finding any reference to it in their "Episode" list.

Thanks

Steve


On Aug 20, 2013, at 12:01 PM, Frank Stellmach <frank.stellmach at freenet.de> wrote:

> Hello,
> 
> until now, nobody has ever reenginered the 732B schematics. Perhaps the bbs.38hot colleagues (lymex et. al.) have done that, but I do not get access to the forum for downloading anything, either.
> 
> But on eevblog, the Datron 4910 reference element has been decrypted completely, as now the content of the Vishay resistor array is known.
> Yep, I have to admit, that I also have made much more effort there than here lately. See 'Ultra precision reference LTZ1000'.
> 
> Anyhow, in the 732B manual, there is that circuit block diagram, showing the usual reference amplifier circuitry.
> Fluke added some current cancellation circuitry compared to the 732A, and has put all temperature sensitive components inside the oven.
> That includes especially the 4-5 precision wirewound resistors around the ref. amp., which cause the most drift over temperature and time.
> 
> I think that's all with 732Bs magic.
> 
> The 732B had two series, one earlier with the SZA263 (Motorola) and after termination of that part, a compatible 2nd source from LT, the LTFLU refence amplifier.
> 
> The mentioned Fluke / Deaver document analyses the different drift behaviour of those two components, but in general, the 732A (based  on the SZA263) was less stable, afaik.
> 
> Frank
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