MFJ MFJ-869 - Frequency Counter Calibration; Wattmeter Calibration

MFJ-869 MFJ Giant automatic SWR/Wattmeter Instruction Manual
© 2009-2010 MFJ Enterprises, Inc.
11
Frequency Counter Calibration
To calibrate the frequency counter, you will need a transmitter, a 50-ohm dummy load, two 50-ohm SO-
239 coax cables, a Phillips screwdriver, and a tuning tool or small flat blade screwdriver.
WARNING: Do not touch anything inside the wattmeter during operation! Serious, painful RF
burns can result.
WARNING: Never operate the MFJ-869 with its cover removed; dangerous voltages and
currents can be present during operation. Never exceed wattmeter specifications.
1. Turn off the power to the unit and the transmitter.
2. Remove the cover from the unit (4 screws) with a Phillips screwdriver.
3. Connect the 50-ohm dummy load to the ANTENNA connector and connect the transmitter to the
TRANSMITTER connector on the unit.
4. Turn on the power to the transmitter. Set and lock the frequency to exactly 29.000 MHz.
5. Press and hold both the [MODE] and [ALARM] buttons while turning the power on. The analog
meter needle will go to full scale.
6. Key the transmitter to output about 10 watts. Adjust trimmer capacitor VC2, located next to the big
integrated circuit, until the analog meter needle settles at the 0-watt mark. Notice the meter
movement is exaggerated for easier calibration. Nominal tolerance of the frequency counter is ±1
kHz.
7. Turn off the power to the unit and the transmitter.
8. Secure the cover back onto the unit.
Wattmeter Calibration
To calibrate the meter needles, you will need a Phillips screwdriver and a tuning tool or small flat blade
screwdriver.
1. Turn off the power to the unit and the transmitter.
2. Remove the cover from the unit (4 screws) with a Phillips screwdriver.
3. Press and hold both the [PEAK] and [ALARM] buttons while turning the power on. The analog
meter needle will bounce. Release the buttons.
4. Use a small flat blade screwdriver and adjust the trimmer, located below the analog meter, to set the
analog meter needle to the 0-watt mark.
5. Press the [MODE] button to calibrate the needle to full scale.
6. Adjust trimpot VR8, located to the left of the big integrated circuit, to set the analog meter needle to
full scale of 20/200/2000-watt mark.
7. Press the [MODE] button to end calibration and resume normal operation.
8. Secure the cover back onto the unit.