[time-nuts] HP5065A C-field current is temperature sensitive
Poul-Henning Kamp
phk at phk.freebsd.dk
Mon Aug 31 06:28:53 UTC 2015
--------
In message <55E39AF2.2050708 at rubidium.dyndns.org>, Magnus Danielson writes:
>Ehm, eh... that transistor pair you have there. How *tight* together is
>really the transistors thermal connection? I bet not all that good.
They're in the same TO5, but I don't know if they're the same die.
I have about 45-50 microvolt difference between their bases.
>Anyway, the take-away is that you should look at that discrete
>op-amp and see if it is not causing you the thermal dependence you are
>trying to locate. Maybe replace it with a more modern op-amp like the
>741 or something (irony may have been used).
Yes, that is absolutely the plan.
The integrator and AC-amplifier in the HP5065 gets upgraded to
chip op-amps in later revs, but this one does not.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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