MFJ-269D Instruction Manual LF/HF/VHF/UHF SWR Analyzer
2
1.0
INTRODUCTION
The MFJ-269D is a compact battery powered RF impedance analyzer. It combines five basic circuits; a
variable oscillator, frequency counter, frequency multiplier, 50-ohm RF bridge, twelve-bit A-D converter,
and a microcontroller. Together, these circuits perform a wide variety of useful antenna and RF
impedance measurements including coaxial cable loss and electrical distance to an open or short.
Although mainly designed for analyzing 50-ohm antenna and transmission line systems, the MFJ-269D
also measures RF impedance from a few ohms to several hundred ohms. An easy-to-access user-
controlled Zo setting in the
Advanced
function menus facilitates changing SWR and other SWR
functions (i.e. return loss, reflection coefficient, match efficiency, etc) to any normalized impedance
value between 5 and 600 ohms. The MFJ-269D also functions as a non-precision signal source and
frequency counter. Operating frequency extends from 0.10 to 230 MHz in nine overlapping bands with
extended SWR measurement from 415 to 470 MHz.
1.1
Typical Use
The MFJ-269D may be used to adjust, test, or measure the following
:
Antennas: ...................................SWR, impedance, reactance, resistance, resonant frequency, and
bandwidth
Antenna tuners: ..........................SWR, bandwidth, frequency
Amplifiers: .................................Input and output matching networks, chokes, suppressors, traps, and
components
Coaxial transmission lines: ........SWR, length, velocity factor, approximate Q and loss, resonant
frequency, and impedance
Filters: ........................................SWR, attenuation, and frequency range
Matching or tuning stubs: ..........SWR, approximate Q, resonant frequency, bandwidth, impedance
Traps: .........................................Resonant frequency and approximate Q
Tuned Circuits: ..........................Resonant frequency and approximate Q
Small capacitors:........................Value and self-resonant frequency
RF chokes and inductors:...........Self-resonant frequency, series resonance, and value
Transmitters and oscillators:......Frequency
The MFJ-269D measures and directly displays the following:
Electrical length (feet or deg)
Impedance phase angle(degrees)
Resonance (MHz)
Feedline Loss (dB)
Inductance (
µ
H)
Return loss (dB)
Capacitance (pF)
Reactance or X (ohms)
Signal Frequency (MHz)
Impedance or Z magnitude (ohms)
Resistance or R (ohms)
SWR (Zo programmable)
The MFJ-269D is also useful as a non-precision signal source.
It provides a relatively pure
(harmonics better than -25 dBc) signal of approximately 3 Vpp (~20 mW) into a 50 ohm load. The
internal source impedance is 50 ohms. Although not "stabilized", it provides adequate stability for non-
critical applications such as alignment of broad-bandwidth filters and circuits.