MFJ-998RT Legal Limit IntelliTuner
TM
Automatic Remote Antenna Tuner Instruction Manual
© 2011 MFJ Enterprises, Inc
MFJ-998RT Version 1A
22
Relay Test
WARNING:
Turn off the transmitter power or disconnect the transmitter before performing this test; otherwise,
damage to the tuner can result.
To test the relays and their control circuitry, press and hold the [C-DN] button while turning the power on.
The message RELAY TEST will appear. Six numbers representing the relays will be shown on the
display. The [ANT], [C-UP], [L-UP], [MODE], [C-DN] and [L-DN] buttons, corresponding to the position of
the relay numbers on the display, are used to toggle each relay on and off. Press button to engage the
relay and release it to disengage the relay. Listen for relay clicks. Press the [TUNE] button to proceed to
the next group of six relays. There are 31 relays in the tuner. Repeat the above procedure to test all the
relays. Normal operation is resumed after this test. Relays K2 and K31 are not included on the board so
there will be no click on those relays.
SWR Bridge Calibration
To calibrate the SWR Bridge, you will need a transmitter capable of 100 watts output, a precise calibrated
wattmeter, a 50-ohm dummy load, three 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 tuner during operation!
Serious, painful RF burns can result.
1. Turn off the power to the tuner and the transmitter.
2. Remove the cover from the tuner (12 screws) with a Phillips screwdriver.
3. Connect the 50-ohm dummy load to the ANTENNA 1 connector; connect the watTMeter between
the transmitter and the TRANSMITTER connector on the tuner.
4. Turn on the power to the transmitter. Using a frequency in the middle of the HF band, such as
7.253 MHz, for calibration is recommended.
5. Press and hold both the [C-UP] and [L-UP] buttons while turning the tuner power on.
6. A message CAL CAP AND FWD will display. Key the transmitter to output 100 watts and adjust
trimmer capacitor VC1 (located on the small circuit board mounted in front of the TRANSMITTER
connector) for minimum reflected power. Notice the reflected meter movement is exaggerated for
easier calibration.
7. Key the transmitter to 100 watts output and adjust the FWD trimpot VR1 (located next to the big
integrated circuit) until the display shows forward power of FWD=100 watts. The forward meter
also should indicate 100 watts.
8. Press the [TUNE] button. A message REVERSE, CAL REF displays and the reflected meter goes
to full scale.
9. 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.
10. Turn on the transmitter’s power.
11. Key the transmitter to 100 watts output and adjust the REF trimpot VR2 (located next to the big
integrated circuit) until the display shows reflected power of REF=100 watts. The forward meter
(yes, the forward meter) also should indicate 100 watts; the reflected meter is at full scale.
12. Press the [TUNE] button to end calibration.
13. Turn off the power to the tuner and the transmitter.
14. Remove the transmitter/watTMeter and the 50-ohm dummy load from the tuner.
15. Secure the cover back onto the tuner.
16. Connect your transmitter to the TRANSMITTER connector and connect your antenna to the
appropriate antenna connector on the tuner.
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.
