Text preview for : efratom_model_frs_lamp_assembly_repair.pdf part of EFRATOM efratom model frs lamp assembly repair . Rare and Ancient Equipment EFRATOM efratom_model_frs_lamp_assembly_repair.pdf
Back to : efratom_model_frs_lamp_as | Home
11/06/2008
EFRATOM Model FRS-C 10MHz Rubidium Clock.
Model FRS-C
Most surplus EFRATOM units found today are more then 15 years old. Due to there age and condition of operation, many
may be considered by some to be at the end of there life.
I believe that age and period of continuous operation is not the big contributing factor to end of life, scrap the unit to the junk
draw.
It is component failure due to long exposures to high heat that causes failure to more then 99% of the 20 units I have repaired,
The following is a result of repairing 20 units over a period of 3 months around 4 years ago. 3 months included some brief
study of the Zeeman affect and how Rb resonance works
The main area to consider is within the physics package. There are two essentially 2 blocks that need careful consideration,
they are:-
1. The lamp and lamp support board, the support board that holds the Rubidium lamp housing.
2. Resonator cavity and heating ring & circuit.
Z1 +24 vdc
Z2 +12 vdc
Figure 1, Lamp assembly & PCB's Z3 +17 vdc
The Rubidium (Rb) lamp does not have a filament. The function of the lamp assembly is to generate the right Rb Spectral
lines ~ (768nm). Rb light ( Plasma ) is generated as a result of a 80~100 MHz oscillator and heat generated from the lamp
support housing.
Figure 1 above shows the lamp ignited as a result of +24 vdc on pin Z3 as shown, the photo shows a blueish discharge. Once
ingited, cut back the Z3 voltage to +17 vdc.
Next add +12 vdc toZ2 and then +24vdc to Z1. The current consumption on the +24vdc rail should be approx. 400mA. After
about 2 minutes when the housing is temperature stabilized to approx. 84 degrees C, the following should be observed:-