MFJ-259D
$$$··
| Frequency | 0.1-230 MHz (100 kHz to 230 MHz), plus the 2200 m / 137 kHz region; adds 100-160 kHz and 280-520 kHz ranges over the earlier 259C |
| Bands | HF (1.8-30 MHz), 6m, 2m, 1.25m (220 MHz), 0.1-230 MHz analysis |
| Power | An antenna analyzer, not a transmitter. It contains a low-level RF signal generator (about 1.8-170 MHz) used to measure a connected antenna or cable; it does not produce transmit-level RF. |
| Modes | Antenna/cable analysis plus RF signal generator and frequency counter (SWR, R, X, Z, L, C, coax tools) |
| Weight | 684 g (24.1 oz) |
| Year | 2018 |
| antenna | SO-239 (UHF/PL) antenna/test port, 50 ohm |
| dc in | External 12 V DC through the optional MFJ-1312D supply, or 10 internal AA batteries |
| power req | 10 AA alkaline or Ni-MH batteries (not included), or 110-240 VAC through the optional MFJ-1312D supply; built-in Ni-MH/Ni-Cd charger, battery saver and low-battery warning. |
A do-everything analog antenna analyzer at a moderate price: SWR, full complex impedance (R+jX or Z and phase), return loss, coax loss and length, distance-to-fault, and L/C measurement, plus a frequency counter and signal generator, across 100 kHz to 230 MHz including the 2200 m band. You tune it like a radio, the dual meters and LCD are easy to read, and it runs on AA cells or mains.
It is now discontinued (MFJ stopped manufacturing in 2024), so it is end-of-life even where stock remains. It is an analog instrument without the charts, memory or PC link of a vector analyzer, the batteries are not included, and at around $350 it costs more than a basic SWR meter, which is the trade for the measurement features.
The MFJ-259D is the most-developed version of MFJ's long-running analog antenna analyzer, covering 100 kHz to 230 MHz plus the 2200 m band and reading SWR, complex impedance, coax loss and length, distance-to-fault and L/C, with a frequency counter and signal generator built in. It suits an operator who wants a simple, tune-like-a-radio analyzer for building and trimming antennas and feedlines; those who want charts, memory and a PC link choose a vector analyzer, and it is now an end-of-line purchase.
The MFJ-259D is the most fully developed version of MFJ's long-running analog antenna analyzer, the instrument many hams reach for to build and trim antennas. It covers 100 kHz to 230 MHz plus the 2200-meter (137 kHz) region, and you use it like a transceiver: connect the feedline, set the bandswitch, and tune the dial while the analyzer shows SWR, complex impedance, return loss and frequency all at once on a two-line LCD with a pair of analog meters. Because it generates its own low-level signal, you can check an antenna across and outside the ham bands without transmitting.
It does much more than SWR. It reads complex impedance as resistance and reactance (R+jX) or as magnitude and phase, finds an antenna's resonant frequency and 2:1 SWR bandwidth, and on coax it measures velocity factor, loss in decibels, electrical length, and the distance to a short or open in feet. It also measures inductance and capacitance at the operating frequency, and it combines a frequency counter, an RF signal generator, and an L/C meter in the same box. The D model added two low-frequency ranges (100-160 and 280-520 kHz) over the earlier 259C.
For connection it uses a standard SO-239 (UHF) test port on 50 ohms. It runs on ten AA cells (alkaline or Ni-MH, not included) or from the mains with the optional MFJ-1312D supply, and has a built-in charger and battery saver. The case is rugged all-aluminum, about 4 by 6.75 by 2 inches and 684 grams. It is now discontinued, as MFJ ceased manufacturing in 2024, though stock remains at some dealers.
It is the analog, tune-by-hand approach to antenna analysis. The earlier MFJ-259C is its predecessor, while the RigExpert AA-230 ZOOM and the low-cost NanoVNA add charts, memory and a PC link as digital alternatives.