[time-nuts] Any experienced HP 2804A thermometer users out there?

Henk Termeer henk.termeer at gmail.com
Sat Jan 24 11:16:41 EST 2009

Hello John,

A temperature probe measures only it's own temperature, keep this in mint if
you are using a probe. What I mean is this if you make contact to a solid
warmer object, you will have a small contact surface, and a large prope to
heath. Depending on the temperature difference you will get a huge error.
Because the probe radiates energy to the enviroment, this gives a gradient
on the probe so your quartz cristal will never get the same temperature as
the object. This error can be anything between 0,1 and 5 degrees Celcius
depending on the object temperature and the enviroment temperature and makes
all the digits behind the afther the "," useless
To minimize the error you can increase te contact area, lower the thermal
resistance between the probe and the object, isolate the probe, etc.
For surface temperature measurement, I think your probe is not the best
solution, a thermocouple could be a better solution.
The best thing is to make an error budget and see what is the best solution
for your problem.

Best regards,


PS maybe you can post a small photo or drawing of the object you want to

On Sat, Jan 24, 2009 at 4:42 PM, John Ackermann N8UR <jra at febo.com> wrote:

> The temperature probes for the 2804A quartz thermometer seem primarily
> intended for liquid immersion.  I'm looking for practical tips on how to
> couple the probe to a solid surface (e.g., a PC board) for accurate
> temperature measurements of the surface.
> Anyone know the best way to do this?
> Thanks,
> John
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