I don't think it's really the short term zero stability you need to be concerned with (though that's important too). I think it's the long term stability of the zener and how predictably it behaves with temperature. I agree that by now it is likely that the zener has improved beyond its original behaviour, but remember that in theory at least the 7071s got the "reject" zeners that weren't up to scratch for use in the 7081.
Of course if there weren't enough orders for 7081s that week, it is quite possible that "good" zeners ended up in 7071s!
PS If anyone has an unrepairable 7061/7071/7081 with a working display, I'm still looking for one.
Dave
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On Behalf Of m k
Sent: 18 April 2012 14:41
To: volt-nuts@febo.com
Subject: [volt-nuts] 7071 stability question
Hi everyone.
I have an old 7071 that looks remarkably stable. I have got two thin strands of TCW and twisted them together then put an end in each of the outer sockets of the connector. left the unit on for a day then zeroed it, now abot a day or two later it is slowly moving between 0.00 and 0.17 microvolts on the 3.2 second averaging. How does this compare with any 7081's anyone has? my guess is that it has aged into 7081 spec, but I want to be sure before desoldering the link LK17 and carefully cleaning it.I intend to use IPA clean, and pure to remove any conductive muck and reduce leakage later.
Regards,
M K
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and follow the instructions there.
I don't think it's really the short term zero stability you need to be concerned with (though that's important too). I think it's the long term stability of the zener and how predictably it behaves with temperature. I agree that by now it is likely that the zener has improved beyond its original behaviour, but remember that in theory at least the 7071s got the "reject" zeners that weren't up to scratch for use in the 7081.
Of course if there weren't enough orders for 7081s that week, it is quite possible that "good" zeners ended up in 7071s!
PS If anyone has an unrepairable 7061/7071/7081 with a working display, I'm still looking for one.
Dave
-----Original Message-----
From: volt-nuts-bounces@febo.com [mailto:volt-nuts-bounces@febo.com] On Behalf Of m k
Sent: 18 April 2012 14:41
To: volt-nuts@febo.com
Subject: [volt-nuts] 7071 stability question
Hi everyone.
I have an old 7071 that looks remarkably stable. I have got two thin strands of TCW and twisted them together then put an end in each of the outer sockets of the connector. left the unit on for a day then zeroed it, now abot a day or two later it is slowly moving between 0.00 and 0.17 microvolts on the 3.2 second averaging. How does this compare with any 7081's anyone has? my guess is that it has aged into 7081 spec, but I want to be sure before desoldering the link LK17 and carefully cleaning it.I intend to use IPA clean, and pure to remove any conductive muck and reduce leakage later.
Regards,
M K
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