MFJ-1642 Portable Whip Tuner
Instruction Manual
3
4) The transmitter power may now be increased up to a maximum of 150 watts.
Note:
The MFJ-
1642 will reduce the SWR of most antenna systems to below 1.5:1.
In Case of Difficulty
If this tuner
fails to tune,
please double check all connections and follow the tuning procedure again.
The power rating of this tuner is 150 watts on 80-10 meters. If this tuner
arcs
at the rated power
levels, please double-check all connections and follow the tuning procedure again.
If you are still unsuccessful, please read the following ANTENNA HINTS text.
Grounding Hints
To minimize RFI, antennas should be kept away from other wiring as much as possible. Also, the
antenna should be adequately insulated to prevent arcing or accidental contact if placed near other
objects.
For safety, it is always best to use both dc and RF grounds. A DC ground may not be practical in
some portable locations, however.
It is always important to have a good RF ground, provided by the counterpoise, when using any whip or
long-wire antenna. This is because the MFJ-1642 tuner needs something to "push" against in order to
force current into the antenna. If a good RF ground is not available, RF will usually find its way back
into the power line (RFI), transmitter audio circuits (RF feedback), or the operator (RF burns).
Water pipes provide good dc and ac safety grounds, but they are often inadequate for RF grounding
because they are long single conductors. RF grounds require large "spread out" surfaces with direct
multiple connections to the equipment ground point. Water pipes, heating ducts, or multiple ground
rods may work (especially if they are all connected together with jumper wires), but the best RF
grounds are radial systems or multi-wire counterpoises.
Antenna Hints
WARNING:
For operator safety, a good earth ground should be installed and connected to
the case of the MFJ-1642. Make certain the safety ground connects to the
same terminal that connects to the transmitter and other station accessories.
A binding post labeled "COUNTERPOISE" is provided for counterpoise or
other RF ground connection(s). This post
will not
provide a safety ground.
