Reasons for shutting the Maser off.
3:1) The thing to look for is the Ion Pump Current. It should be stable. If it has a trend or just is varying, this means the ion pump elements have to be replaced.
You have to keep a log of regular measurements to see this.
Instructions for turning the Maser OFF.
1) First read all the meters and record these readings and all settings.
2) The safest way to turn off the maser, even for periods as brief as possible, is first to turn off the SOURCE and VALVE breakers.
To accelerate the valve cooling, remove the heater from the Palladium valve, by sliding it off. (Careful! It will be HOT!!).
To do this you need to open the top lid of the maser.
Watch the dissociator pressure [PRESS] and when it has dropped to about 20%, also the ion pump current [5MA] to below 50%, then turn off the PUMP breaker.
3) You can then turn off the THERMAL breaker and shut down the MAIN breaker.
Normally you should not shut down the THERMAL and MAIN breakers.
Note: All breakers are on the rear side of the maser.
Instructions for turning the Maser ON.
1) To reactivate the maser turn on the main, THERMAL and PUMP breakers as soon as possible and allow the ion pump current [5MA] to stabilize. If it has been switched off too long you will not be able to start it. One has to use external power supply and vacuum pump it again.
2) Then turn on the VALVE breaker and let it stabilize to the previous palladium valve heater [VALVE] voltage.
3) Then turn on the SOURCE breaker and check that its voltage to source oscillator [SOURCE] and source oscillator current [SOURCE CURRENT] are back to normal.