MFJ-933C
High-Efficiency Magnetic Loop Tuner
Instruction & Technical Manual
2
THE MFJ-933C
2.1
INTRODUCTION
The MFJ-933C
High-Efficiency Magnetic Loop Tuner
™
(Figure 3) is a small, versatile,
high-efficiency device that turns any wire or coax loop into a high-efficiency multi-band
transmitting loop antenna system designed for a 50Ω input impedance and 150W RF power on all
modes. It consists of two primary components:
•
MFJ-933C
High-Efficiency Magnetic Loop Tuner
™
•
Wire or Coax Loop (not included)
The MFJ-933C
Deluxe High-Efficiency Magnetic Loop Tuner
™
has two functions. First, it uses
various lengths of wire to create a very-high-Q tuned circuit that is used as a transmitting loop
antenna. An MFJ-19 low-loss Butterfly capacitor with no rotating contacts (available separately
for your own homebrew projects) is the heart of this circuit. The second function is as a matching
network that matches the high-Q transmitting loop circuit to your 50Ω coaxial cable.
Figure 3: The MFJ-933C
RF grounds, radials, or a counterpoise system are not required, though a safety ground is
recommended. While the MFJ-933C
High-Efficiency Magnetic Loop Tuner
™
can tune any shape
loop (circle, square, rectangle or any odd shape), a wire or length of coaxial cable approaching a
quarter wavelength shaped as a circle is the most efficient configuration.
The MFJ-933C
High-Efficiency Magnetic Loop Tuner
™
uses fixed-length wires or coaxial cables
which will create a Standing Wave Ratio (SWR) around 1.5:1. Exact frequency coverage depends
on each individual installation’s choice of wire or coax length and diameter, shape of the loop,
height above ground level, and operating environment.
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Summary of Contents for MFJ-933C
Page 18: ...USER NOTES ...
