MFJ-998 IntelliTuner
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| Frequency | 1.8-30 MHz |
| TX power | 1500 W (1500 W SSB and CW (legal-limit class), across the 12-1600 ohm matching range. Auto-bypasses above 1500 W. Powered by 12-15 V DC at ~1.4 A.) |
| Modes | SSB, CW, AM, FM, digital |
| Weight | 3.7 kg (8.2 lb) |
| Connector | SO-239 x2 (ANT1/ANT2) |
| rf in | SO-239 (from transmitter/amplifier) |
| rf out ant1 | SO-239 (antenna 1; mutually exclusive with the WIRE post) |
| rf out ant2 | SO-239 (antenna 2) |
| wire | binding post (random wire; shares with ANT1 - use one or the other) |
| ground | wing-nut ground post |
| radio interface | multi-pin radio-interface connector (optional MFJ-5114I/K/Y cables for Icom/Kenwood/Yaesu/Alinco auto-tune) |
| amp enable | Amp Enable In + Amp Enable Out RCA jacks (bypass/key an external amplifier during tuning) |
| serial | DB-9 (RS-232) for firmware updates |
| dc in | 2.1 x 5.5 mm barrel, 12-15 V DC (~1.4 A) |
| power req | 12-15 V DC at ~1.4 A (2.1 x 5.5 mm barrel; some sources list 1.3 A); 110 V AC via optional MFJ-1316. A 3 A supply is advised for heavy relay switching. |
Estimated (unverified): Introduction year is not documented. Weight is ~8 lb (3.7 kg) per the manufacturer and one EU listing; a US retailer lists 9 lb. Tuning-combination count is 81,664 per the manual (a few sources compute 81,920).
A true legal-limit automatic tuner: it matches a kilowatt at full power across 12-1600 ohm with 20,000 memories for instant recall. Its standout feature is the Amplifier Bypass Control, which removes the dangerous habit of tuning at full amplifier output - it bypasses the amp, tunes on a low-power carrier, then restores it, and protects the amp if it cannot match. It is not single-brand (Icom/Yaesu/Kenwood interface cables), has both analog and digital metering, and was notably compact and affordable for its power class.
The matching range bottoms out at 12 ohm, higher than some rivals, and it has no built-in balun (balanced line needs the external MFJ-912). Being relay-switched, it finds one of its fixed combinations rather than matching continuously like a roller-inductor tuner, and the relays clack while tuning. Interface cables are extra, it wants a stout 12 V supply, and it is HF only. MFJ quality varies, and it is discontinued.
A legal-limit automatic tuner that does the job most amplifier operators want - hands-off matching at 1,500 watts with the amp safely bypassed during the tune. It is relay-switched rather than a continuously variable roller design (that is Palstar's HF-AUTO, at roughly double the price), and it needs an external balun for balanced line, but for a kilowatt station into coax-fed multiband antennas it was a capable, comparatively affordable choice. Now a used-market item since MFJ closed.
The MFJ-998 is MFJ's legal-limit automatic tuner - the IntelliTuner scaled up to handle a full 1,500 watts, so it can sit between an amplifier and the antenna and match impedance at full power. Press tune or transmit, and it works through a relay-switched L-network - banks of fixed toroidal inductors and capacitors, some 81,000 combinations, clicked in by heavy 16-amp relays - to find a match across 1.8 to 30 MHz, anywhere from 12 to 1,600 ohms.
The feature that makes it sensible at this power is the Amplifier Bypass Control. Tuning an amplifier at full output is a classic way to destroy expensive parts; the 998 instead drops the amp out of line, keys the radio for a low-power carrier, finds the match, and only then puts the amplifier back in - and if it cannot get the SWR down, it keeps the amp bypassed to protect it. It stores 20,000 settings for instant retune, switches between two coax antennas, and reads out on both an analog cross-needle meter (300- or 3,000-watt scales) and a backlit LCD.
Like the smaller IntelliTuners it is not single-brand: optional cables let an Icom, Yaesu, or Kenwood radio command the tune, and there are RCA amp-enable jacks, a serial port for firmware, and the usual SO-239s plus a wire post (which shares with antenna 1). Two things to note: it has no built-in balun, so balanced line needs the external MFJ-912, and its relay-switched design - while it always finds one of its fixed combinations - cannot match as continuously as a true roller-inductor tuner.
That last point is the heart of the comparison: the only legal-limit automatic tuner that uses a continuously variable roller inductor and air capacitor is Palstar's HF-AUTO, which matches more precisely and reaches 6 meters but costs about double. For an operator who wants hands-off tuning behind a kilowatt amplifier and does not mind the relay clack, the MFJ-998 did the job at a much lower price - and MFJ also made a weatherproof feedpoint version, the 998RT. It steps up from the 300-watt MFJ-993B; for manual tuning at this power the Palstar AT2K is the premium choice, and it pairs with a kilowatt amp like an ACOM 1000. MFJ stopped manufacturing in 2024, so it is now a used-market item, last around $770.