LDG IT-100
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| Frequency | 1.8-54.0 MHz |
| TX power | 125 W (0.1-125 W SSB/CW (100 W on 6 m); 30 W maximum on PSK/digital modes. Powered by the Icom radio through the tuner-control cable - no separate supply. (~5 W minimum to start a tune cycle.)) |
| Modes | all |
| Weight | 750 g (26.5 oz) |
| ant | ANT: SO-239 (to the 50-ohm antenna feedline) |
| tx | TX: SO-239 (coax jumper to the radio's antenna jack) |
| radio | Radio interface: 6-pin mini-DIN at the IT-100, with a 14 in cable to a 4-pin Molex (friction-fit) plug that mates the Icom TUNER jack; carries both DC power and the KEY/START tune-control lines |
| ground | wing-nut ground terminal |
| power req | Powered entirely by the Icom transceiver through the TUNER-jack interface cable; no external supply or DC jack |
Estimated (unverified): Introduction year is not documented by LDG (it replaced the AT-7000; manual is Rev A). Weight figures conflict: the manual states ~1 lb while dealer and European listings report ~0.75-0.8 kg (used here). Dimensions are ~6.5 x 6.5 x 1.5 in per dealer listings; the manual's spec page lists 7.25 x 6.25 x 1.75 in.
An Icom auto-tuner that behaves like a built-in one: it plugs into the radio's tuner jack, draws its power from the radio, and tunes from the front-panel TUNE button - no extra supply, no extra controls. It widens the match well beyond a typical Icom internal tuner, handling up to 10:1 SWR and 4-800 ohms across 160-6 m, and its latching relays hold the match with zero power, so a stored setting is instantly valid at switch-on. 2,000 memories make band changes immediate, and at ~0.75 kg it is compact.
Icom only - it needs a radio with the AH-3/AH-4 tuner jack. Power tops out at 125 W (100 W on 6 m, just 30 W on digital), so it is barefoot-only and FT8 operators must reduce power. A ladder-line or random-wire antenna needs an optional 4:1 balun. The 4-pin radio plug is a friction fit with no latch and can loosen. And it is discontinued - now a used-market buy - from a small company (LDG) whose continuity has been questioned.
For an Icom radio that lacks a built-in tuner, or whose internal tuner quits at 3:1, the IT-100 is the tidy answer: it powers from the radio, tunes from the TUNE button, holds the match without power, and reaches a 10:1 mismatch. The 30-watt digital limit and Icom-only design are the constraints. Now discontinued in favor of LDG's Z-100A, it is a used-market pickup - essentially a desktop, lower-cost alternative to Icom's own AH-4.
The IT-100 is LDG's answer to a quirk of Icom radios: many have a jack on the back for an automatic tuner but no tuner inside, or an internal tuner that only stretches to a 3-to-1 mismatch. Plug the IT-100 into that TUNER port and it behaves like Icom's own AH-4 - the radio powers it through the cable, disables any internal tuner, and drives the whole thing from the front-panel TUNE button. There is no separate power supply and no extra controls to learn; you press tune and a second or two later you are matched.
What it adds over the radio's built-in tuner is range. It matches from 4 to 800 ohms - up to a 10-to-1 SWR (3-to-1 on 6 meters) - across 1.8 to 54 MHz, where most Icom internal tuners give up at 3-to-1. With an optional 4:1 balun it reaches toward 3,200 ohms for ladder-line and random-wire antennas. Inside is the familiar LDG switched-L network, but with latching relays: once it finds a match it holds those relay positions with no power at all, so the setting survives turning the radio off and is instantly valid again at power-up. It stores 2,000 of them for instant band changes.
The limits are the ones you would expect of a radio-powered box. It handles 125 watts on SSB and CW, 100 on 6 meters, and only 30 on the digital modes - so FT8 and RTTY operators have to keep the power down. It is Icom-only by design; Yaesu owners use the equivalent YT-100, and anyone wanting a brand-agnostic version uses LDG's Z-100Plus. The interface cable is mildly notorious: a friction-fit 4-pin plug at the radio with no latch, which can work loose.
It pairs naturally with tuner-jack Icoms like the IC-718 (set its menu to AH-4) and the IC-7300, giving them the wide-range tuner they lack - essentially a desktop, lower-cost stand-in for the feedpoint-mounted AH-4. LDG has since discontinued it and points buyers to the newer Z-100A, so it is now a used-market item; as with the rest of the LDG line, the company is small and its continuity has been questioned, so confirm support before relying on it.