MFJ-249B Instruction Manual
HF/VHF SWR Analyzer
2
MFJ-249B HF/VHF SWR ANALYZER
INTRODUCTION
The MFJ-249B SWR analyzer is an easy to operate, versatile test instrument for analyzing nearly
any 50 ohm RF system on frequencies between 1.8 and 170 MHz. In addition the MFJ-249B can
be used as a signal source and as an accurate frequency counter.
The MFJ-249B combines four basic circuits; a wide range oscillator, a frequency counter, a 50
ohm RF bridge, and a microcontroller. This combination of circuits allows measurement of the
SWR (referenced to 50 ohms), magnitude of the impedance, components of the impedance
(resistance and reactance), of any load connected to the
ANTENNA
connector. By connecting a
signal to the BNC jack labeled
FREQUENCY COUNTER INPUT
it is possible to determine
its frequency
The MFJ-249B provide a sinewave signal of approximately 3 Vpp to any load in series with a 50
ohm internal resistance. The unit
FREQUENCY
switch selects the following frequency ranges:
1.8 - 4 MHz
4 - 10 MHz
10 - 27 MHz
27 - 70 MHz
70 - 114 MHz
114 - 170 MHz
The MFJ-249B can be used to adjust or measure the following:
Antennas:
SWR, impedance, resistance, resonant frequency, bandwidth,
efficiency
Antenna tuners:
SWR, frequency
Amplifiers:
Input and output networks
Coaxial transmission lines:
SWR, velocity factor, losses, resonance
Matching or tuning stubs:
SWR, resonance frequency, bandwidth
Traps: Resonant
frequency
Tuned Circuits:
Resonant frequency
Small capacitors:
Value
RF chokes and inductors:
Self resonance, series resonance, value
Transmitters and oscillators: Frequency
The MFJ-249B is also portable. It can be used with either an external low voltage supply, such
as the MFJ-1315 AC adapter or with internal AA battery packs.
WARNING:
Please read this manual thoroughly before using this instrument. Failure to
follow the operating instructions may cause false readings or even damage this
unit.
