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Trouble Shooting: Beam too strong
When you are getting a very high reading on PDA-18, such
as more than 6 mA on a 2 (the switch on the right) x 4 (the SCALE) scale,
or the direct beam test complains
with a message "direct beam too strong", the beam is considered to be too
strong. First try beam alignment again. See
if the PDA-18 reading changes when you manipulate the mirrors. If not, that's
a pretty good indication that you are getting the white x-ray. In this case,
check BIAS setting on the front panel. Also, check if there is any filament
grounding or improper connection of filament terminals (you need to open
up the x-ray tube).
In some rare cases, you are getting normal readings on PDA-18 but very high
recorded on image plate. This means
that you've forgotten to put the beam stopper on the collimator when you
took the direct beam shot. Do it again with the stopper on.
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