[time-nuts] Environmental sensor recommendations

[David C. Partridge]

> The OCXO is not the temperature problem with the Tbolt. It is the DAC.

So is there a better one that can be used to replace it?

David

-----Original Message-----
From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of ew via time-nuts
Sent: 05 April 2018 10:43
To: time-nuts at febo.com
Subject: Re: [time-nuts] Environmental sensor recommendations

I respectfully disagree. The OCXO is not the temperature problem with the Tbolt. It is the DAC. Again this is not a product developed for time nuts it did an excellent job for its intended purpose. Over a year we worked on the Tbolt using HP 10811, OSA 8600, FRK Rb, M100 Rb with excellent Warren support.
Using up to 40 000 seconds and 6 E-17 per uV we probably know more about the Tbolt than any time nut. The DAC on the Tbolt is worse than 1 E-10, we have experimented with temperature control of the board. As a matter of fact the OCXO contributes to a certain amount of temperate stability.
Attila visited Juerg and me on my Europe trip and observed 3 Tbolt's, original, 8600 and M100 in operation. Tracor 527 showed the jumps of the original.
We plan on using the OCXO's pulled as offset OCXO's on our latest D/M project.
Bert Kehren 
 
In a message dated 4/4/2018 11:46:09 PM Eastern Standard Time, holrum at hotmail.com writes:

 
 Lady Heather has a very nice temperature control PID in it (designed by Warren Sarkisen). It was originally designed to stabilize the temperature of a Thunderbolt GPSDO. The standard Thunderbolt OCXO is rather temperature sensitive. 

The standard/simple implementation involves sticking the Thunderbolt in a cardboard box with some thermal mass and baffling. Heather then PWMs a fan (at 1 Hz, using the serial port modem control signals and a DC solid state relay) to mix room temperature air into the box. It can control the temperature readings to around 0.01C with long term RMS errors in the low microdegree range (absolute accuracy depends upon the temp sensor).

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> I would suggest that if you are looking at taking temperature sensor 
> data
and attempting to control some type of heating/cooling device that you implement a PID loop for stability.
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