[time-nuts] HP5065A environmental sensitivities

Bob Camp kb8tq at n1k.org
Sun May 22 13:25:15 EDT 2016


Hi

In 40 years of getting phone calls, the one that never seems to go away starts out with:

“We … errr… measured the temperature rise in our box and need to adjust the upper end
temperature on your part”.

The really interesting part is that you can get multiple calls that go the same way from the 
same engineering team. Each time they drop in another board or check a rack in a customer
installation new data arrives …

A 5C rise is nothing. Some of these boxes run at 95C with what is supposed to be 50C inlet air. 

Bob



> On May 22, 2016, at 12:33 PM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> 
> --------
> In message <B1C92A76-2349-48DB-9FA5-F95F5D31AB02 at n1k.org>, Bob Camp writes:
> 
>> At least 5C offset relative to an external sensor. Likely more in some rack
>> installations. Past that it depends on how close the item of
>> interest is to the oven assembly.
> 
> That's only part of it.
> 
> The rather important zener diode regulating the C-field is located
> on the DC regulator board, where the temperature depends directly
> on the grid voltage...
> 
> -- 
> 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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