Being a Shera Fan I finally broke down and bought a Tbolt. I experimented with a foam enclosure with roughly 1 centimeter on all sides. What I found that it only increased the board temperature by 19 C. It was still as sensitive to ambient. Thanks to Lady Heater it even shows an increase of 40 mC when I walk up to it with one minute delay.. Changing to an aluminum extrusion the increase is only 7 C and the response is much slower. In its final assembly it will be inside a larger metal mass, I do not think that the higher temperature of 56 C is conducive to longer life. Opinion: putting foam around a 10811 will only give you a warm feeling unless you make it much larger than shown in the picture of of KH6GRT. Based on the above test results I feel mass is more important. So I took a aluminum enclosed dewar weighing 943 gr. and did first put a resistor in it and heated it up with 2 W. Temp. did rise to 70 C. Next I disassembled my worse 10811, which is very easy, since it is a nice compact unit and inserted it in the dewar. Monitoring temp with my YSI it shows 65.2 C with 24 C ambient. Power dissipation is 1.575 W. Will track it over time before I replace the 10811 with one of my better ones for frequency tests. Questions to our experts: A) will Removing the foam mess with the temp. control loop B) How low can total power into the 10811 be before temp control can become a problem, I think I am ok now, but once in a chassis with Shera and power and battery the temp. surrounding the dewar may become a problem. C) What is the preferred orientation of the unit. I asked already once before if any one has data on the 1 1 PPS output of the Tbolt over time, since I am considering it as an alternative to a stand alone GPS receiver, and if there are GPS receivers that outperform a Tbolt what is the recommendation. It will be used to control a Rb. Bert Kehren In a message dated 1/7/2011 8:22:51 P.M. Eastern Standard Time, [email protected] writes:
Has anyone experimented with the amount of insulation on a 10544 or 10811 oscillator? They are meant to run hot by design and I worry that adding any insulation, or too much insulation, will either cause over-heating or limit the ability of the oven control to maintain the set point. None of the hp/Agilent bench test equipment that uses these oscillators uses insulation. Perhaps that's a clue. /tvb _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
