EFRATOM efratom model frs lamp assembly repair free download

File name efratom_model_frs_lamp_assembly_repair.pdf

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:-