MFJ-925 Super-Compact IntelliTuner Automatic Antenna Tuner
Instruction Manual
©
2006 MFJ Enterprises, Inc.
20
6. Press and hold
only
the [ALT] button while turning the power on. Both LEDs will blink until the
button is released.
7. Within four seconds of releasing [ALT], 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 and TRANSMITTER connections; that is,
connect the 50-ohm dummy load to the TRANSMITTER connector and connect the
transmitter/wattmeter to the ANTENNA 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
ANTENNA connector on the tuner.
In Case of Difficulty
If the tuner acts erratic, reset the tuner to factory defaults.
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.
Summary of Contents for MFJ-925
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