[time-nuts] HP5065A C-field current voltage mod
Poul-Henning Kamp
phk at phk.freebsd.dk
Fri Sep 4 10:13:35 EDT 2015
--------
In message <20150904152721.RKIe37Zb at smtp14.mail.yandex.net>, Charles Steinmetz
writes:
>Perry wrote:
>
>>OK, but why? The temperature would be stable so the resistorsand
>>reference diode wouldn't drift.
>
>There is a LOT more to making a good temperature-controlled
>environment than hacking together a DIY oven. That may be fine for
>stability of tenths of a percent (10e-3), but when stability of
>10e-13 is at issue it doesn't pay to start with 50ppm parts and put
>them in a DIY oven. You need to start with low-tempco parts.
I actually have some calculations relevant to this, I'll write them
up on my homepage when I have a second.
The short version is that voltage reference noise above 5PPM will
be a limiting factor on performance.
--
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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