Low Dose rate

Error: Photons, Dose Rate drops after a good start.

The Gun Servo depends on good Slit signals. If one of the slits is in bad condition the servo will not work correct. Check Gun control part 1 and 4.

Check if tuner position runs into the tuner upper limits, about 340. At this time you need to change the magnetron, or investigate if the following tricks work.

When magnetron power is decreased (lower PRF) frequency will decrease and the magnetron is back in its working range. Check if mag. power is matching electron energy (change bending coarse up and down to see if dose rate drops. If it is matched, don't touch it anymore. The next step is putting the magnetron in High Power Mode. This looks contradictory, but in this mode the PRF is halved resulting in a lower average power. It is possible that the dose rate, at this new tuning, will be a bit lower than in Low Mode.

Changing mag. mag. will alter the impedance and hence the frequency generated by the magnetron. So this may have a positive effect on the tuner position. Of course the impedance of the magnetron should remain at 225 Ohm to match the PFN. Check PFN-V