Re: [volt-nuts] Solartron 7071 vs 7081
They aren't identical. The 7071 is a 7.5 digit meter, the 7081 is 8.5
digits. They have many components in common, though. I believe the
reference Zener in th 81 is selected and aged, there may well be other
differences, most likely selected resistors, etc. I'm also not sure the
71 has the 2nd-order temp compensation for the Zener, but take that with
a grain of salt.
That said, there may well be a jumper, I'll have to take a look at mine
and see if I can identify it. I'd expect it to be on the processor
board. But, even so, enabling 81 won't give you the accuracy of an 81.
Here's a link to a (poorly scanned) spec sheet:
http://www.mbmt.com/data/7071_7081.pdf
--
Bill Ezell
They said 'Windows or better'
so I used Linux.
Bill
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.
Dave
Hi David,
It sounds like you just have to close the circuit for the missing "8 nines" button.
Robert G8RPI.
From: David C. Partridge david.partridge@perdrix.co.uk
To: 'Discussion of precise voltage measurement' volt-nuts@febo.com
Sent: Wednesday, 4 April 2012, 1:50
Subject: Re: [volt-nuts] Solartron 7071 vs 7081
Bill
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.
Dave
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Dave,
Is it possible you have a 7081 that has been converted to a 7071 by
replacing the front panel? How difficult is it to remove and replace the
front panel?
Joe
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On
Behalf Of Robert Atkinson
Sent: Wednesday, April 04, 2012 6:13 AM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] Solartron 7071 vs 7081
Hi David,
It sounds like you just have to close the circuit for the missing "8 nines"
button.
Robert G8RPI.
From: David C. Partridge david.partridge@perdrix.co.uk
To: 'Discussion of precise voltage measurement' volt-nuts@febo.com
Sent: Wednesday, 4 April 2012, 1:50
Subject: Re: [volt-nuts] Solartron 7071 vs 7081
Bill
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.
Dave
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