MFJ-1642 Portable Whip Tuner
Instruction Manual
1
MFJ-1642 Portable Whip Tuner with Artificial Ground
IMPORTANT:
Please read entire manual before attempting to operate this equipment. This unit does
not provide a dc or low frequency earth ground from the counterpoise terminal. A separate wire should
be connected from the station ground bus to an electric ground. Do not place any counterpoise or non-
coaxial feed wires near metallic or RF sensitive devices.
Introduction
The MFJ-1642 is a 150 watt, 80-10 meter antenna tuner designed for tuning short whips as well as
virtually any random length wire antenna. It is perfect for either fixed station or portable use, and, with
its built-in artificial ground tuning system, will match any transmitter or transceiver to virtually any
antenna.
The MFJ-1642 tuner section uses a reversible "L" network. The advantage of the “L” network is that it
has only two tuning controls, and only one tuning solution for given impedance match. The MFJ-1642
has rear panel connectors for coaxial input and a “Hi-Z/Lo-Z” switch for reversing the “L” network. An
internal input-isolating current balun provides isolation of DC and RF grounds for optimum tuning of the
RF counterpoise.
MFJ-1642 Supplied Components (30-10 meter operation)
•
MFJ-1956 12 ft. telescopic whip antenna
•
Counterpoise assembly (6, 14, and 26 ft. long wires)
MFJ-1642 Optional Components ( 40-80 meter operation)
•
MFJ-63 Loading Coil Assembly for 40-80 meter operation with the MFJ-1956 12 ft.
telescopic whip antenna
Installation
1. Locate the MFJ-1642 in a convenient location at the operating position. Avoid placing the tuner
near microphones, speech processors, computers, TNC's or other RF sensitive devices.
WARNING: High RF voltages exist at the antenna and counterpoise terminals. Avoid
touching these terminals while transmitting!
2. Connect your transceiver’s output to the SO-239 (UHF female) connector labeled
TRANSMITTER on the back of the tuner. You will need an external SWR Wattmeter connected
in line between the transmitter and whip tuner.
