[time-nuts] Z380XA The saga of the aging 10811

[Bob Benward]

Hi Ed,
OK, a bad oven.  I can buy that.  But then if the oscillator is constantly
drifting, would that not imply that the oven is constantly changing
temperature, in one direction?

BTW, the curve is starting to flatten out.  It might be flat before It gets
to 1000K counts.

Bob

>>> -----Original Message-----
>>> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of ed
>>> breya
>>> Sent: Tuesday, September 08, 2015 10:55 AM
>>> To: time-nuts at febo.com
>>> Subject: Re: [time-nuts] Z380XA The saga of the aging 10811
>>> 
>>> It could be that the inner oven temperature regulation is off a bit, or
even
>>> failed. There was a report at one of the popular time-nuts oriented
websites (I
>>> forget which one, but it's the one that had extensive coverage of the
Z3801A)
>>> about inner oven problems a few years ago. I took mine apart and found
that
>>> it had an IC of a particular date code range that was prone to failure.
I can't
>>> recall whether I replaced it with the same type but different date, or
an
>>> alternative, but it worked just fine after that, with no tweaking of
coarse EFC
>>> needed.
>>> 
>>> The IC was a dual opamp I think, that controlled the oven temperature
>>> according to the thermistor signal, and drove the heater transistor(s).
>>> It was a fairly high performance type, but not that unusual. I think it
was a
>>> Linear Technology brand part.
>>> 
>>> Ed
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