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MFJ-1642 Portable Whip Tuner
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.
1
Instruction Manual
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Table of Contents
Related Manuals for MFJ MFJ-1642
Summary of Contents for MFJ MFJ-1642
- Page 1 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.
- Page 2 MFJ-1642 Portable Whip Tuner Instruction Manual 3. Connect the MFJ-1956 12 ft. telescopic whip antenna to the 3/8x24 stud on the top of the unit. For 40-80 meter operation with the MFJ-1956, you will need the optional MFJ-63 coil assembly.
- Page 3 MFJ-1642 Portable Whip Tuner Instruction Manual 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.
- Page 4 This occurs when the antenna is approximately a half-wavelength long at the frequency at which you are trying to tune. MFJ-1642 Artificial Ground The MFJ-1642 contains a series L-circuit that is used to tune the RF ground system (either a counterpoise or a ground wire). The MFJ-1642 will achieve minimum SWR when the COUNTERPOISE switch is properly set.
- Page 5 If the station ground has a long lead, you can connect it to the COUNTERPOISE binding post of the MFJ-1642. Connect the station ground bus and accessories to the GROUND post. Do not reverse these wires. Follow the same procedure for minimizing SWR described in the tuning procedure.
- Page 6 MFJ-1642 Portable Whip Tuner Instruction Manual Tuning Chart You may wish to remove or make a copy of this page and place it near the tuner. Insert your own values for each frequency according to your station. Freq MHz Counterpoise...
- Page 7 MFJ-1642 Portable Whip Tuner Instruction Manual Schematic...
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