[volt-nuts] Solartron 7071 vs 7081
David C. Partridge
david.partridge at perdrix.co.uk
Wed Apr 4 00:50:32 UTC 2012
Here's an extract from an email from one of the guys who worked at Solartron for a long time and is still there now that it is Ametek:
>Incidentally did you know that the 7081 and 7071 are essentially the same instrument?
>The reference zener diodes were soaked for several weeks in an oven which temperature
>cycled them and each diode was checked regularly for stability. The very best ones were
>selected to go in the tighter specified 7081. The not so good ones went in the 7071.
>Otherwise the only difference is the front panel and the contents of the EPROMS.
>The 7081 has an 8 x nines (51 seconds integration time) button. On the 7071 this button
>is not present and the firmware limits the integration time to 3.2 seconds (7 x nines
>display). Both units can go down to 3 nines (1.56mS integration time, 100 readings per
>second when under remote control although of course this rather defeats the object of
>having such an long scale instrument.
Hence my surprise to see ROMs clearly labelled 7081 in a 7071 meter, and it does not think it is a 7081. Apart from the front panel and external labelling there's sweet little visual difference between it and my 7081 (internally as well as externally). I've not found any candidate jumpers thus far, and I have looked.
So yes, I do realise that even if it were possible to fool the firmware that wouldn't magically turn the 7071 into a 7081.
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