and frequency measurement
Subject: Re: [time-nuts] Rb cooling
For all of this attention to cooling the oven on the Rb standards,
has anyone seen any failures that are attributable to heat?
I sort of doubt it.
-Chuck Harris
ewkeh...@aol.com wrote:
> I monitor and fan cool the base plate, sta
On 18/07/11 06:40, Chuck Harris wrote:
I understand that, but you didn't answer my question:
Has anyone seen any failures that are attributable to heat?
50 year theoretical life vs 75 theoretical year life probably
isn't going to be too significant. 1 year life vs 10 year would
be.
These GPSDO
same thoughts almost the same fan mine are 50 mm square and less than 10
mm. Mine are from a dead plasma display.
Best regards
Bert
In a message dated 7/17/2011 10:15:41 P.M. Eastern Daylight Time,
charles_steinm...@lavabit.com writes:
Bert wrote:
>Charles sounds like what I am doing. W
Chuck wrote:
Cooling down an oven is not a good thing, as it simply ups the
power the oven control circuitry dumps into the oven to keep it
hot.
The temperature, thermal mass, and conductivity of the surroundings
determine how quickly an oven cools down when the heater is off. Too
little co
I understand that, but you didn't answer my question:
Has anyone seen any failures that are attributable to heat?
50 year theoretical life vs 75 theoretical year life probably
isn't going to be too significant. 1 year life vs 10 year would
be.
These GPSDO's are made to run with their ovens pow
The manufacturers data sheet presents MTBF figures for the LPRO
and they decline considerably with higher temperatures.
Against that the power required decreases with rising temperature,
so that at 19 volt supply and 40-45*C the unit takes much lower
power and has
still has most of its expecte
For all of this attention to cooling the oven on the Rb standards,
has anyone seen any failures that are attributable to heat?
I sort of doubt it.
-Chuck Harris
ewkeh...@aol.com wrote:
I monitor and fan cool the base plate, stays nice and constant at 45 C
which I can not say with heat sink onl
Bert wrote:
Charles sounds like what I am doing. What size fan do you use?
It's 40 mm square, and quite thin (< 10 mm), from a dead hard
drive. At normal indoor temperatures (20-25C), it spins from 100-200 rpm.
I chose 45C for the baseplate temperature so it can be used at any
ambient tem
Charles sounds like what I am doing. What size fan do you use?
Bert
In a message dated 7/17/2011 9:13:42 P.M. Eastern Daylight Time,
charles_steinm...@lavabit.com writes:
Poul-Henning wrote:
>Cooling Rb's should happen only through the base-plate.
>For frequency stability, you should stri
Poul-Henning wrote:
Cooling Rb's should happen only through the base-plate.
For frequency stability, you should strive to have a constant
baseplate temperature.
I mounted an FRS-C in an unvented cast aluminum box by its baseplate
(after cleaning up the mating surface in the box on a mill t
On 18 July 2011 11:12, WB6BNQ wrote:
> Thinking about it Poul,
>
> That explains why the preferred "frying pan" is made of cast iron in
> deference to
> the modern light weight ones they sell these days; better temperature control
> across the cooking area. I knew I was saving old used cast iron
I monitor and fan cool the base plate, stays nice and constant at 45 C
which I can not say with heat sink only. I am considering lowering the base
plate to 40 C. I have a heat sink on the base plate with the fan blowing over
it. Makes good heat exchanger. I have experimented with heat pipes f
Thinking about it Poul,
That explains why the preferred "frying pan" is made of cast iron in deference
to
the modern light weight ones they sell these days; better temperature control
across the cooking area. I knew I was saving old used cast iron pans for a
reason. Now I know what I am going t
Cooling Rb's is a much misunderstood discipline.
Most Rb's have a specified "base plate temperature range".
For instance the PRS10 specifies -20..+65°C
Cooling Rb's should happen only through the base-plate.
Cooling other surfaces creates unwanted temperature gradients inside
the Rb unit.
The
I use on several Rb's a small 5 X 5 X 1 cm Nidec 60 mA fan with a linear
temp regulator. I can not hear it and it is mounted on the outside back
plate of the chassis with the Rb on the other side of the back plate. In one
case I have the fan mounted with four rubber grommets inserted in th
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