[time-nuts] -hp- 10811 repair (Thermistor)

[Dan Rae]

Bruce Griffiths wrote:
> Meanwhile, before posting a correction I was trying to find data on the
> oven setpoint temperature tolerance.
>
> The relevant HP Journal with an article on the HP10811A is:
> http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf
>
> One concern is:
> How accurate does one' thermometer which one uses to calibrate the
> thermistor bridge setpoint have to be?
>
> Bruce
>
>
>   
Bruce, I'm guessing that since they quote values of R20 in the manual in 
intervals of 0.1 Degrees, that is how close they got.  Except oddly 
enough for 83.9 and 84.0 degrees, which are the same, but shouldn't be, 
IMHO.  I don't claim to have got that close in my thermistor tests, 
maybe 0.5 degrees using a lab type mercury thermometer.  But my original 
point is still valid: I now have a working oven.  In my case I will use 
an external reference for the 5370B so it is kind of not that important 
anyway...

Dan