Fluke Biomedical 07-492 - Manual (Page 17)

Calibration and Adjustment
Lo Battery Threshold Adjustment
5
5-1
Section 5
Calibration and Adjustment
The Model 07-492 kVp Meter has been factory calibrated. Any calibration should be done by the factory
or a qualified calibration facility. The unit should be calibrated once a year by adjusting the five variable
resistors as discussed in the following sections.
5.1 Lo Battery Threshold Adjustment
Resistor R25 adjusts the threshold for the LO BAT indication on the LCD Display. Use the following
procedure to adjust R25:
1. Remove the battery.
2. Connect a variable DC power supply to the instrument at the battery connector cable.
3. Connect a voltmeter between battery plus (TP3) and analog ground (TP4).
4. Turn on the power supply and adjust it to 9 Volts.
5. Turn on the kVp meter. The voltmeter should read between 2.4 and 3.2 V.
6. Slowly decrease the power supply until the voltage across the test points just returns to the value it
had prior to dropping off.
7. Turn R25 until LO BAT disappears from the display.
8. Turn R25 slowly in the opposite direction just until LO BAT reappears on the display.
9. Connect the voltmeter between analog ground and the power supply negative terminal.
10. Increase the power supply voltage until the voltmeter reads 4.5 V while being careful not to exceed
9V from the power supply. LO BAT should be off at this point.
5.2 kVp Calibration Adjustments
The following are some guidelines to ensure proper calibration of the kVp meter:
1. An independent accurate means of measuring the x-ray machine is necessary.
2. The kVp meter must be calibrated at 26 kVp, 30 kVp, and 40 kVp (± 1 kVp) if it is to be within
specification over its entire range.
3. The potentiometers must be adjusted interactively as detailed below.
4. Be sure to set the phase switch, located the rear panel of the unit, appropriately.
5. Be sure to follow the procedure outlined below in the order listed.
Use the following procedure for kVp calibration:
1. Set a calibrated Moly Anode/Moly Filter x-ray machine to 26 kVp, with sufficient mAs to obtain a
reading.
2. Locate the Model 07-492 kVp meter in the center of the beam with the cover removed from the
meter.