[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    
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