[time-nuts] 10811 foam enclosure
EWKehren at aol.com
EWKehren at aol.com
Sun Jan 9 19:00:03 UTC 2011
Thanks for all the info. Agree after my tests on the Tbolt, that is why I
will place large mass around it, will keep it close to ambient and move
What is the zero G axis?
Presently oven current is 65 mA down from 95 at room temp so I have room to
go but I will monitor over ambient changes, presently we have lows in the
60's but it has been as high as 82 in the last week.
I try if possible to stay away from any additional heating or cooling, the
only exception is on the Rb's where I experiment with small variable speed
fans and laptop heat pipes in cooling the base plate to 42 C.
In a message dated 1/9/2011 1:42:19 P.M. Eastern Standard Time,
warrensjmail-one at yahoo.com writes:
>Q) Has anyone experimented with the amount of insulation on a 10811
a) Look inside a double oven 10811 to see one example of what works.
>Q) None of the hp/Agilent bench test equipment that uses these
>oscillators uses insulation. Perhaps that's a clue.
a) It is not much of a clue, considering that a patent & knowledgeable
time-nuter can get 10 to 100 + better performance out of them.
Look inside a HP Z3801 GPS.
>Q) "how far can you go"
a) One way is to monitor the Oven current. If it goes to near zero you
I've found a 50% to 75% reduction in heater current from its room
temperature value works.
A separate issue is if you are cooking the electronics outside of the oven.
>Q) too much ... can cause over-heating or instability.
a) To see if the oven controller is becoming unstable,
Just monitor the Oven current and plot how it resettles after making
changes of a couple volts to the oven voltage or change its case
>Q) What is the preferred orientation of the unit.
The Zero G tilt axes. The position that tilting the unit a slight amount
any axes causes the freq to shift in the same direction.
comment) What I've found to be very effective is to place a paper towel
around the osc and put it in a plastic baggie to keep it from generating
air currents on its own.
Then put that inside of an enclosure that does not have holes, and Hold
enclosure's outside temperature constant.
I find this technique works great for both Tbolts and 10811's. Easy to get
10 - 100 to one improvement with a little care.
IMHO, You do not need, or even want, to raise the case temperature of a
Tbolt anymore than absolutely necessary.
Just need to keep the Tbolts case temperature from changing very fast (or
1 deg F per hr max works OK for most units, or for the extreme time-nut,
for 0.1 degC per hr max rate of change.
To do that, I find mass to be more effective than insulation. (you need
I've gotten the best results using Lady Heather's temperature controller
with a small fan blowing air indirectly at the Tbolt's case.
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