[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 
too far.
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 
very  far).
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 
of both)
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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