LDG AT-1000ProII
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| Frequency | 1.8 - 54.0 MHz continuous (160 through 6 m) |
| Bands | 160m, 80m, 40m, 30m, 20m, 17m, 15m, 12m, 10m, 6m |
| Power | Automatic tuner; power limits by mode: 1000 W SSB, 750 W CW, 600 W FT8, 500 W PSK/digital, 250 W on 6 m. Matches 6-1000 ohms (16-150 ohms on 6 m). |
| Modes | automatic switched-L antenna tuner (non-latching relays) with built-in wattmeter and 2-antenna switch |
| Weight | 1.96 kg (4.3 lb) - About 4 lb 5 oz (~1.96 kg); 11.5 x 9.75 x 3.25 in (Manual Rev D, 2023). |
| rf input | SO-239 from the transceiver |
| antenna | Two SO-239 antenna outputs with a built-in 2-port antenna switch |
| dc in | 11-16 V DC at about 1 A max |
| control | Optional radio-interface cable for one-button tuning with many transceivers |
| power req | 11-16 V DC (~1 A) to power the relays and logic. Tunes automatically on demand. |
Hands-off matching at real power: it automatically tunes coax-fed antennas across 160-6 m up to 1000 watts SSB, remembers 2000 settings per antenna for near-instant retunes, and includes a 2-antenna switch and a built-in forward/reflected wattmeter - a lot of capability in one box. It interfaces with many radios for one-button tuning and runs from 12 V.
It is for coax-fed antennas within 6-1000 ohms - it is not a balanced-line/wide-range tuner for open-wire or extreme loads (no balun). Power derates on CW/digital and especially 6 m, it needs a 12 V supply, and as an automatic L-network it offers less manual control than a roller-inductor tuner.
The LDG AT-1000ProII is a capable 1 kW automatic antenna tuner for 160-6 m with fast memory tuning, a 2-antenna switch and a built-in wattmeter - an excellent hands-off matchbox for a 1000-watt coax-fed station. Operators with balanced line or very extreme loads need a wide-range manual tuner instead.
The AT-1000ProII is LDG's biggest automatic tuner, built to sit between a kilowatt-class amplifier and the antenna and find a match on its own. Like all LDG tuners it uses a switched-L network: banks of fixed capacitors and inductors that a microprocessor clicks in and out through relays until the SWR drops, storing the result so the next visit to that frequency is instant. It covers 1.8 to 54 MHz and matches impedances from 6 to 1,000 ohms (a narrower 16 to 150 on 6 meters).
Power handling is the headline. After it finds a match it will pass 1,000 watts on SSB, 750 on CW, 600 on FT8, and 500 on the steady digital modes, dropping to 250 watts on 6 meters. The catch, and it is an important one, is that the tune itself must happen at low power: you drop to between 5 and about 125 watts to let it search, and its firmware refuses to switch relays above 150 watts to keep the contacts from arcing. So an amplifier is bypassed for the few seconds of the tune, then driven at full power once the relays settle. Those relays are non-latching, which means the tuner needs its 12-volt supply powered up to hold the match.
It is a capable station box: a built-in two-position antenna switch with its own pair of SO-239 jacks, over 4,000 tuning memories split across the two antennas, an LED bar-graph wattmeter with 100- and 1,000-watt scales, and manual fine-tune buttons for stubborn loads. It is a standalone tuner with its own power jack rather than a radio-powered accessory, though optional interface cables let it tune from the TUNE button on many Icom, Yaesu, and Alinco radios. A ladder-line or random-wire antenna needs an external balun ahead of it.
LDG essentially created this category - the company's founder published the first automatic switched-L tuner as a QST construction article in 1996 - and the ProII is the high-power end of a line that runs down through the Z-100Plus and the Icom-specific IT-100. For an amplifier station that wants hands-off tuning across two antennas it is a strong choice, competing with units like the Elecraft KAT500. One caveat: LDG is a very small company whose long-term continuity has been questioned, so it is worth confirming warranty support before buying.