[time-nuts] How to accurately measure an oscillator's temperature.
EWKehren at aol.com
EWKehren at aol.com
Thu Apr 24 13:42:46 UTC 2014
I am not sure if you want to measure temperature or control a fan. To
measure there are many options depending on how much money you want to spend.
To control I suggest either a LM 335 or a NTC resistor. I have worked
extensively with both and for measuring I have now downsized to a YSI. Used to
have a HP XTAL thermometer.
Spend a lot of time and money on temperature control on Rb's and OCXO's all
part of GPSDO's and have come to the conclusion on OCXO's a combination of
thermal Isolation and thermal mass is the best solution and on Rb's fans.
Spend a year playing with concepts on the FE5680 with all kind of fans and
heat sinks and aluminum shapes till it hit me the answer was right in front
of me. In my opinion a fan/heat pipe out of an old laptop is the cheapest
and best solution, low cost, low noise, no special assemblies and easy to
control. Use an aluminum plate as the interface or use the bottom plate
directly and use one of the bottom screws to hold your sensor it is internally
directly tied to the spine of the Rb. Wide variety available on ebay under
In a message dated 4/23/2014 10:38:11 P.M. Eastern Daylight Time,
albertson.chris at gmail.com writes:
I have both an OCXO and an FE-5680 Rb oscillator and I'd like to track
What is the best why to measure? Maybe each has a different best method
The OCXO is just a small steel can. Is measuring the steel can temperature
the best why to go. Epoxy some kind of sensor to it?
The Rb is mounded to a large heat sink and there is a fan. I want to
control the fan so as to keep the Rb temperature constant.
In both cases I tried using TMP36 three terminal sensors and just got
noise. The reported temperature was up and down more than 2C. The fan
controller just chases noise.
BTW the fan based temperature control is effective. The FE5680 gets very
warm in it's box but if I give the 12V fan even 8 volts the heat sink
quickly cools. I want to throttle the fan to keep the Rb at constant
temperature but the temperature data I'm getting is not very good.
The problem I think is that any sensor I have is on the outside of the
oscillator and is effected by cooling air What are others doing? What's
the best kind of sensor.
Redondo Beach, California
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