MFJ-986Differential-TTuner Instruction Manual
8
6. Adjust the CAPACITOR control for lowest reflected power (and SWR).
7. If the SWR did not reach 1:1 in step 5, turn the INDUCTOR control clockwise (to a higher number)
again and repeat Step 5. For maximum power handling and efficiency, always adjust the capacitor
to the lowest front panel number that allows proper antenna matching. This insures maximum
power handling and lowest power loss in the tuner.
8. Advance the power (do not exceed 100 watts) and, if necessary, touch up the CAPACITOR and
INDUCTOR controls for minimum reflected power and maximum forward power (lowest SWR).
Remove the power.
9. After adjusting the tuner for minimum SWR, the amplifier may be turned on. The METER switch
should be placed in the HI position, and the amplifier tuned according to the manufacturer's
instruction.
10. For quick retuning of the tuner, record the INDUCTOR and CAPACITOR settings for each band.
Note:
Maximum power handling occurs when both the CAPACITOR AND INDUCTOR are set at
the lowest front panel numbers for capacitance and highest inductance that permit matching
the antenna. Following this guideline will insure maximum power handling capability and
efficiency, and the least critical tuning adjustments.
Operating Notes
1. While this tuner is designed to have as large a tuning range as possible, there are limits to the tuning
range of the capacitor. Some antennas may require more or less capacitance than the controls have.
In these cases, the SWR may not be reduced to 1:1. If the SWR is higher than the limits on your
rig, try changing the length of the antenna or feedline to bring the impedance within the tuning
range of the tuner.
2. When adjusting the tuner, use the lowest amount of CAPACITANCE and INDUCTANCE that
produces a good SWR. This will reduce tuner losses and increase the power rating of the tuner.
3. If the INDUCTOR counter slips out of calibration, turn the INDUCTOR fully counter clockwise.
Then, with a small screw driver or pencil, push the reset button through the hole to the right of the
counter. This resets the counter to "000".
4. The following table can be used as a guide to tune your MFJ-986 to a specific operating band.
When the MFJ-986 is properly tuned, the counter reading should approximately match the number
on the table. If the counter is too far from the number on the table, then the tuner is not properly
tuned. If this is the case, repeat the tuning process.
BAND INDUCTOR
160 M
80 M
40 M
20 M
15 M
10 M
INITIAL TUNE-UP INDUCTOR SETTINGS
