MFJ-989D VersaTuner V Instruction Manual
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3.) Mechanical Considerations: When setting up, always confirm the Antenna Selector is on the correct
setting and firmly latched in place before applying power. Also, when tuning the rotary inductor, note
that its range spans from 000 to approximately 090 on the counter dial. Crank slowly as you approach
the end settings to avoid slamming the inductor roller into the stops.
4.) Applying Power During Adjustment: If you normally run a high-power amplifier (greater than 100-
W), leave it out-of-line and tune the antenna for a 1:1 match using only your station transceiver (or an
antenna analyzer).
5.) Tube-Type Output Stages: Always pre-tune transceivers or vintage transmitters with a tube-type PA
into a 50-Ohm load prior to routing them through the T-network. Then, leave them set where they are
(normalized to 50-Ohms) and let the tuner do the matching!
Important Warning: Never apply high power to the MFJ-989D before it has been fully adjusted for
minimum SWR. Always tune unknown antenna loads using the least amount of power needed to
obtain a useful SWR reading (25 Watts or less).
6.) Antenna Analyzers: As an alternative to using a transceiver, you may also use an antenna analyzer to
tune an unknown load. Connect the analyzer to the tuner's Transmitter connector, set if for the desired
frequency, and refer to its SWR display as you adjust the tuner's controls. Using an analyzer eliminates
QRM to other stations while you are experimenting to find the best L/C settings.
Step-By-Step Tuning Procedure
Important Warning: Never apply high power during the antenna tuning procedure!
[ ] Switch the Antenna Selector to the desired antenna.
[ ] Set the SWR Meter's Range switch to AVG and set the Power switch to LO.
[ ] Set the Antenna and Transmitter capacitors to the appropriate value shown below:
160 M: 0 20 M: 4
80 M: 1 17 M: 6
75 M: 2 15 M: 7
40 M: 3 12 M: 8
30 M: 3-1/2 10 M: 8-1/2
[ ] Preset Inductor to the highest number (090)
(least amount of inductance).
[ ] Apply low power (25-Watts or less)
[ ] Rotate the Inductor knob counter-clockwise to add progressively more inductance.
[ ] Watching SWR, adjust Inductor for lowest reflected and highest forward Power.
To bring Reflected Power readings lower, continue tuning using the following procedure:
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