MFJ MFJ-941E - Troubleshooting and Band Matching; Troubleshooting Common Issues; Antenna Matching Problems Explained

MFJ-941E Versa Tuner II
5
4. If a SWR of 1:1 is not achieved, the INDUCTOR control should be increased or decreased
and Step 3 repeated. If arcing should occur between capacitor plates, the INDUCTOR
control should be increased or decreased by one position, and Step 3 repeated. If SWR of
1:1 cannot be achieved, Step 3 should be repeated for each INDUCTOR control position.
5.
After a minimum SWR is achieved, transmitter power may be increased to 300 Watts.
The VERSA TUNER II will reduce the SWR of most feed systems to 1:1. In some cases,
a 1:1 SWR is not achievable. In such cases, the length of the antenna may be increased
or decreased to improve SWR.
6. SWR of 1:1 may occur at more than one set of control settings on the MFJ-941E. When
an SWR of 1:1 is obtained, make sure that the transmitter power is relatively high. If
transmitter power has decreased substantially, try another INDUCTOR control setting and
repeat Step 3.
In Case Of Difficulty:
If this tuner fails to tune, please double check all connections and follow the tuning procedures again. Be sure you
are using enough inductance (lowest letter usable for band) and have the capacitors open far enough (highest front
panel number).
If this tuner arcs at the rated power levels, please double check all connections and follow the tuning procedures
again. Be sure you are using the least amount of inductance and the greatest capacitance possible to match the
load on the operating frequency. If you are still unsuccessful, please read the Antenna Matching Problems text below.
Note
:
If this tuner arcs when operating on the 160 meter band, it may be necessary to reduce
transmitter output power.
Antenna Matching Problems:
Most matching problems occur when the antenna system presents an extremely high impedance to the tuner. When the
antenna impedance is much lower than the feedline impedance, an odd quarter-wavelength feedline converts the low
antenna impedance to a very high impedance at the tuner. A similar problem occurs if the antenna has an extremely
high impedance and the transmission line is a multiple of a half-wavelength. The half-wavelength line repeats the very
high antenna impedance at the tuner. Incorrect feedline and antenna lengths can make an antenna system very
difficult or impossible to tune.