MFJ MFJ-928 - Troubleshooting and Difficulties; Addressing Common Issues

MFJ-928 Compact IntelliTuner Automatic Antenna Tuner Instruction Manual
© 2005 MFJ Enterprises, Inc.
20
6. Press and hold only the [ANT] button while turning the power on. Both LEDs will blink until the
button is released.
7. Within four seconds of releasing [ANT], press the [TUNE] button seven
times.
8. After releasing [TUNE] for four seconds, the cross-needle wattmeter shows 100 watts forward
and 20 watts reflected and the SWR Bridge Calibration is initiated.
9. Make sure the cross-needle wattmeter reads 100 watts forward and 20 watts reflected. If not,
calibrate the cross-needle wattmeter.
10. Press the [TUNE] button and both meter needles drop to 0 watt marks.
11. Key the transmitter to output 100 watts and adjust trimmer capacitor VC1 (located in front of the
TRANSMITTER connector) for minimum reflected power. Notice the reflected meter movement
is exaggerated for easier calibration.
12. Key the transmitter to output 100 watts and adjust the FWD trimpot VR1 (located next to the
RADIO INTERFACE connector) until the forward meter shows 100 watts.
13. Press the [TUNE] button and the reflected meter goes to full scale.
14. Turn off the transmitter and reverse the ANTENNA 1 and TRANSMITTER connections; that is,
connect the 50-ohm dummy load to the TRANSMITTER connector and connect the
transmitter/wattmeter to the ANTENNA 1 connector.
15. Turn on the transmitter’s power.
16. Key the transmitter to output 100 watts and adjust the REF trimpot VR2 (located next to the
RADIO INTERFACE connector) until the forward meter (yes, the forward meter) shows 100
watts; the reflected meter is at full scale.
17. Press the [TUNE] button to end calibration.
18. Turn off the power to the transmitter and the tuner.
19. Remove the cross-needle wattmeter from header HD1.
20. Remove the transmitter/wattmeter and the 50-ohm dummy load from the tuner.
21. Secure the cover back onto the tuner.
22. Connect your transmitter to the TRANSMITTER connector and connect your antenna to the
appropriate antenna connector on the tuner.
In Case of Difficulty
If the LCD screen is blank, check adjustment of the contrast control. If no audio is present (with audio
enabled) adjust the volume control.
If the tuner acts erratic, reset the tuner to factory defaults by pressing both the [TUNE] and [L-UP]
buttons while turning the power on.
If the tuner fails to tune, please double check all connections and follow the tuning procedures again. Be
sure you are using enough inductance (through manual adjustment) and minimum capacitance.
If the tuner arcs at the rated power levels, please double check all connections and follow the tuning
procedures again. Ensure you are not exceeding the tuner’s rated power handling capability. Be sure you
are using the least amount of inductance and the greatest capacitance possible that still allows matching
the load on the operating frequency.
Note: If the tuner arcs when operating on the 160-meter band, it may be necessary to reduce
transmitter output power.
If you are still unsuccessful, but the tuner does adjust and operate when used with a dummy load or
another antenna, please read “Grounding Hints” and “Antenna System Hints” on page 13.