Fluke Biomedical 956A-201-M2 - Manual (Page 88)

5-10
High and Low Discriminator Adjustments
The low discriminator should be set to + 0.5 V +/- 0.01 Vdc, while the high discriminator should be set to
+7.0 +/- 0.01 Vdc unless otherwise specified in the detector calibration.
The following factory adjustments are included for general information and should not be performed in the
field.
Anti-jam Threshold Adjustment (Factory Adjustment Only)
This adjustment is dependent on the type of detector used. Potentiometer VR12 is used to adjust the DC
level measured at R94. Table 5-6 shows the DC adjustment values necessary for each detector type
unless otherwise specified.
Table 5-6. Anti- Jam Threshold Adjustment
Test Pulse Width Detector Type DC Value at R94 Equivalent mR/h Jumper J7
10 microsecond
(50 kHz square wave) 897A Series
G-M Detector Family 0.740 V 897A-21X 3.16 x 10 3
897A-22X 2.14 x 10 4
897A-23X 2.50 x 10 5
2 to 3
Write Cycle Clock Adjustment (Factory Adjustment Only)
1. Connect the channel 1 oscilloscope (x10 probe) to U19-2 (clock).
2. Connect the channel 2 oscilloscope (x10 probe) to U19-12 (short 02).
3. Adjust VR13 to obtain: