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Covers requirements and warnings for using an external DC power supply, including voltage and current specifications.
Explains how to access and set the internal jumper for battery usage before installing batteries.
Provides guidelines for using rechargeable batteries, including voltage requirements and charging procedures.
Offers advice on using alkaline and zinc-cell batteries, including storage and leakage precautions.
Provides essential instructions for connecting devices to the analyzer's antenna and power connectors.
Explains the five basic operating modes of the analyzer and how to navigate between them.
Offers practical advice for making secure RF connections and minimizing errors during SWR and impedance measurements.
Guides users on how to measure SWR for antennas, including static discharge precautions and tuning adjustments.
Provides connection specifics for advanced measurements, including VFO output and ESD protection.
Guides on connecting the analyzer to an antenna tuner and adjusting it for a 1:1 SWR.
Covers requirements and warnings for using an external DC power supply, including voltage and current specifications.
Explains how to access and set the internal jumper for battery usage before installing batteries.
Provides guidelines for using rechargeable batteries, including voltage requirements and charging procedures.
Offers advice on using alkaline and zinc-cell batteries, including storage and leakage precautions.
Provides essential instructions for connecting devices to the analyzer's antenna and power connectors.
Explains the five basic operating modes of the analyzer and how to navigate between them.
Offers practical advice for making secure RF connections and minimizing errors during SWR and impedance measurements.
Guides users on how to measure SWR for antennas, including static discharge precautions and tuning adjustments.
Provides connection specifics for advanced measurements, including VFO output and ESD protection.
Guides on connecting the analyzer to an antenna tuner and adjusting it for a 1:1 SWR.
The MFJ-259D is a compact, battery-powered HF/VHF SWR Analyzer designed for a wide range of RF impedance measurements. It integrates a 50-ohm bridge, an eight-bit micro-controller, a frequency counter, and a 0.10-230 MHz variable-frequency oscillator with switched coverage across nine overlapping bands. This combination allows for comprehensive analysis of 50-ohm antennas and transmission line systems, as well as general RF impedance measurements from a few ohms to several hundred ohms. Beyond its primary function as an impedance analyzer, the MFJ-259D also serves as a discrete signal source (RF-Signal Generator) and an independent frequency counter.
The MFJ-259D is primarily used to adjust, test, or measure various RF components and systems. Its core capabilities include:
The device displays a variety of parameters, including cable length (feet), cable loss (dB), capacitance (pF), inductance (uH), impedance or Z magnitude (ohms), impedance phase (degrees), reactance or X (ohms), resistance or R (ohms), resonance (MHz), return loss (dB), signal frequency (MHz), and SWR (referenced to 50 ohms).
As a non-precision signal source, the VFO output is leveled at approximately 3-Vpp (around 20 milliwatts into a 50-ohm load). This signal is relatively pure, with harmonics better than -25 dBc, and an internal source impedance (Zo) of 50 ohms.
The MFJ-259D offers both basic and advanced operating modes.
Upon power-up, the analyzer displays a sequence of screens showing its software version, copyright, and power source voltage. The default operating mode is "Impedance R&X," which is most frequently used for routine antenna adjustments. In this mode, the top line of the display shows the VFO Frequency in MHz and the numerical SWR reading. The lower line displays the Resistive (R) and Reactive (X) impedance components. Analog meters simultaneously show SWR and Impedance Magnitude (Z), which are particularly useful for continuous tuning of circuits like ATUs. Pressing and holding the "Gate" button in this mode displays Impedance Magnitude (Z) and Phase Angle (Ø).
Other basic modes, accessible by tapping the "Mode" switch, include:
Accessed by simultaneously pressing and holding the "Gate" and "Mode" buttons, the Advanced Menu offers additional measurement modes:
The MFJ-259D can be powered by an external DC supply (11-16 VDC at 150 mA, positive center pin) or internal "AA" type batteries.
To extend battery life, the analyzer features a "Sleep Mode" that reduces current drain to under 15 mA by shutting down the RF generator. The analyzer enters sleep mode after two minutes of inactivity (no mode switch actuation or frequency adjustment). A blinking "SLP" message indicates sleep mode. To reawaken, momentarily press the "Mode" or "Gate" button. Sleep mode can be temporarily disabled by holding the "Mode" button during power-up.
A blinking "VOLTAGE LOW" warning appears if the external DC source or battery voltage drops below 11 volts. Measurements made under low voltage conditions may not be reliable. Pressing "Mode" during this warning will disable it, allowing continued testing.
The analyzer's accuracy is influenced by:
For any problems not resolved by the manual, technical assistance is available via phone, FAX, or e-mail. When contacting support, it is helpful to have the unit, manual, and a detailed description of the problem and usage context ready.
The MFJ-259D comes with a full 12-month warranty covering defects in material and workmanship from the date of purchase, provided the original owner retains dated proof-of-purchase. MFJ Enterprises, Inc. will repair or replace defective products at its option. The warranty does not cover kits, products installed in owner's cabinets, or consequential damages. Out-of-warranty service is also available for a fee.
General| Frequency Display | LCD |
|---|---|
| Display | LCD with backlight |
| Battery Life | Approximately 20 hours |
| Weight | 1.5 lbs |
| Power Supply | 12V DC |
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