MFJ VersaTuner III - Operation

MFJ-962E Instruction Manual
6
dummy load attached to the BYPASS coax connector. Adjust the transmitter according
to the manufacturer's instructions into the 50 ohm dummy load before adjusting the tuner.
Most modern solid state transceivers do not require adjustments. If the transceiver has a built in
antenna tuner, be sure it is turned off or disabled.
After properly preparing the transmitter, place the MFJ-962E ANTENNA SELECTOR switch
in the desired antenna position in the COAX 1 BYPASS or COAX 2 BYPASS setting. If the
SWR is low (very little or no reflected power), the tuner can be left in this position.
If the SWR is higher than desired, place the ANTENNA SELECTOR switch in the COAX 1 or
COAX 2 setting to select the desired antenna. Adjust the tuner as described below to obtain the
best SWR. Do NOT change the transmitter's tuning (plate) or loading (antenna) controls until
AFTER the tuner has been fully adjusted. The transmitter can be "touched up" (if necessary)
after the MFJ-962E is fully tuned to minimum SWR.
Operation
The roller inductor has maximum inductance at "000" and minimum inductance about "125" on
the reference counter. The capacitors have minimum capacitance at 0 and maximum capacitance
at 10. In simple language, as the frequency is increased, the normal control positions rotate
clockwise just like on other equipment.
Note: Always use the most capacitance (settings closest to 0) for the most power handling and
the least loss. Use the smallest possible inductance (the highest number possible) also.
Note: The MFJ Air Core™ Roller Inductor is designed with an exclusive Self-Resonance
Killer™ that keeps potentially damaging self-resonances away from your operating
frequency. This feature is switched in and out of the circuit with a built-in switch in the
roller. Therefore, as you turn the roller up and down, you may feel a bump about mid
range. This is normal and you should not be alarmed.
Increase the number the controls are set at (on a given frequency) to INCREASE the matching
range. Remember, this LOWERS the efficiency and power handling capability of the tuner.
1. Tune the exciter into a dummy load (most solid state transmitters are "pre-tuned" to 50 ohms
and do not require adjusting with the dummy load).
2. Select the desired antenna with the ANTENNA SELECTOR.
3. Position the ANTENNA and TRANSMITTER controls at the following settings:
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