MFJ -834 Instruction Manual

MFJ-834 RF Ammeter

Introduction

Congratulations on purchasing the MFJ-834 RF Ammeter. The MFJ-834 is designed for
measuring in-line RF feedline current on 1.8-30 MHz while having low interaction on the
primary line. Connect the Coax In-Line RF Ammeter between your antenna and tuner/
transmitter/amplifier and measure antenna feedline current in 3 calibrated ranges: .3
Amperes, 1 Ampere, and 3 Amperes.
Uses
• Use it for tuning your antenna tuner/transmitter/amplifier for maximum radiated
power, for determining antenna feedpoint impedance, for comparing antennas and
tuners, for troubleshooting and for checking for changes.
• Tuning for maximum feedline current for any given antenna always gives
maximum radiated power. Any adjustment that increases feedline current
improves power transfer and gives you a stronger radiated signal. Radiated power
increases rapidly because power increases as the square of the current.
• Minimum SWR does not always mean maximum radiated power. Your tuner or
lossy coax may be dissipating power and you may not get peak output power even
if your tuner or amplifier is properly tuned.
• Use the MFJ-834 RF Ammeter to determine best antenna tuner settings and to
compare various tuners. Calculate your antenna feedpoint impedance by dividing
your applied power by the square of the feedpoint current.
• Your antenna can change when you apply power. Insulators break down, traps
heat up, capacitors leak and your feedpoint impedance may be drastically
different from your SWR Analyzer measurements.
IMPORTANT:
Please read entire manual before attempting to operate this equipment. This
unit does not provide a dc or low frequency earth ground. A separate wire
should be connected from the station ground bus to an electric ground. Do
not place any non-coaxial feed wires near metallic or RF sensitive devices.
MFJ-834 RF Ammeter
1
Instruction Manual