[time-nuts] Lamp for FRK Rubidium Needed

[Chuck Harris]

Paul's description is spot on.

A few of things to note:

1) The melting point of Rb is 39C (100F), so it
doesn't take a lot of heat to melt it... but it needs
to evaporate, which takes a little more.  Basically,
once it melts, the amount of Rb that can be made a gas
depends on the pressure in the bulb, and the temperature.
Once you reach the vapor pressure of Rb for the given
temperature you can't evaporate any more.

2) What you are trying to do is clear all of the excess
Rb that has plated out on the glass and move it as a metal
ball to somewhere it won't get in the way of the light
getting to the filter cell, and the detector.

3) I suspect the bulb is pyrex, but I am not sure of that,
I would suggest treating it like it wasn't.  Don't heat
it quickly, and don't let it cool quickly.  You don't
need to get anywhere near red heat.

To support the bulb, make yourself a loop of steel wire
that you can rest the bulb onto.  What you want is a
loop shaped like a lollipop.  Clamp the stem of the wire
loop in a vise, or something that will hold it.  Don't work
far above the ground, and it would be a good idea to have
a soft landing below the bulb just in case...  (If you had
50 bulbs I would bet that the little bugger would bounce
off of a cement floor without harm... But you have only
one, so count on it shattering...)

Once the bulb is clear, you are done.  The real truth is
once it is clearer than it was, it is going to work better
than it did... When it is all the way clear, it is a good
as it was when it was new, and  should last as long as a
new bulb would have.

-Chuck Harris

Peter wrote:
>
>
> paul swed <paulswedb at ...> writes:
>
>>
>> Chuck is correct I have done this trick on FRS units. The glass clears and
>> the lamp re-ignites and continues to work for a long time. Actually it
>> hasn't failed and this must be 2 years now.
>> Regards
>> Paul
>> WB8TSL
>>