[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  
slowly.
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.
Bert
 
 
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 
>oscillator?
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 
went 
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 
small 
changes of a couple volts to the oven voltage or change  its case 
temperature.


>Q) What is the preferred orientation  of the unit.
The Zero G tilt axes. The position that tilting the unit a  slight amount 
in 
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 
any 
air currents on its own.
Then put that inside of  an enclosure that does not have holes, and Hold 
the 
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, 
go 
for 0.1 degC per hr max rate of change.
To do that, I find  mass to be more effective than insulation. (you need 
some 
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.


ws

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