[time-nuts] HP5061B Cesium Oven Properties

[paul swed]

Donald some great work you are doing and since many of us have 5061s that
are on fumes this is a great way to further extend the life while operating.
The run time may be different for various ovens. If its 83c then it was a
high flux tube. They burned up the Cs at a fasterate to give a better
signal to noise. These are typically option 004 units.
Frankenstein has the fewest Cs and would be an ideal candidate for a cycled
oven since currently it uses a home brew DC oven controller and is quite
easily modified.

Funny this is like restoring an old 1960s class car. The tricks that are
needed.
Regards
Paul
WB8TSL

On Wed, Mar 29, 2017 at 11:02 PM, Donald E. Pauly <trojancowboy at gmail.com>
wrote:

> https://www.febo.com/pipermail/time-nuts/2017-March/104374.html
>
> The cesium oven acts as an evaporator for liquid cesium which melts at
> 28.5° C.  One of our beam tubes has 83°C for its operating
> temperature.  It also calls for a A11R11 and A11R12 of 3.83 K and
> 42.2K which is 3.51K.  Oven power is specified at 2.2V and 0.9A or
> 1.98 W.  Being in a vacuum allows less heater power.  Oven temperature
> is very critical to provide enough cesium in the beam but at the same
> time not wasting it.  A switching power supply runs the oven as well
> as providing 1.2V at 3.4A to the hot wire ionizer which is 4.08 Watts.
>
> It took 10 minutes from a cold start for the cesium oven current to
> drop from being pegged to its final value.  After stabilizing, we
> connected a 470 Ω across the thermistor from the beam tube to shut off
> the heater.  Here is the beam current versus time in minutes as the
> oven cooled off.  Note that it took 17 minutes for the beam current to
> drop to half value.  Continuous lock was maintained.
>
> time beam
> 0     20
> 3     18
> 5     17
> 8     16
> 9     15
> 11    14
> 14    12
> 17    11
>
> We then reapplied oven power and watched the beam current increase and
> oven current decrease.
>
> time beam oven
> 0      16     over 50
> 3       20    missed
> 5       22    missed
> 6       21    15
> 8       20     15
> 10     20     14
>
> Finally we applied oven power from a 35 minute cooldown and waited for
> lock.  If the oscillator oven is stable, the cesium oven will achieve
> lock in only two minutes.  There is no need to waste cesium if you do
> not need the instrument to be locked.
>
> time beam status
> 0      8       unlock
> 2      10     lock
> 3       12    lock
> 4       18    lock
>
> πθ°μΩω±√·Γλ
> WB0KVV
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