LDG Z-100Plus
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| Frequency | 1.8-54.0 MHz |
| TX power | 125 W (125 W SSB / 100 W CW / 75 W FT8 / 50 W other digital; 100 W on 6 m. Tunes from as little as 0.1 W (QRP-friendly). Powered by an internal 8x AA pack or 7-18 V DC; under 1 uA standby thanks to latching relays.) |
| Modes | all |
| Weight | 454 g (16 oz) |
| ant | ANT: SO-239 - to the 50-ohm antenna feedline |
| tx | TX: SO-239 - coax jumper to the radio's antenna jack |
| ground | wing-nut ground terminal |
| radio | Radio: 3.5 mm (1/8 in) stereo jack for optional interface cables (IC-PAC for Icom, Y-ACC for Yaesu, CAT-DIN for Kenwood) |
| dc in | Power: 2.5 x 5.5 mm DC jack, 7-18 V DC, center positive (6 ft cable included) |
| power req | Internal 8x AA battery pack (supplied holder, batteries not included; ~1 year of normal use) OR external 7-18 V DC (~200 mA while tuning, under 1 uA standby) |
Estimated (unverified): Introduction year is not documented by LDG; the Z-100Plus succeeded the original Z-100 in the mid-2010s. It coexists in LDG's catalog with the larger Z-100A (which does not replace it). Some dealer listings show ~5.5 x 5.5 x 1.5 in; the current LDG spec is 5.75 x 5.50 x 1.75 in.
Compact, light, and battery-capable, made for portable, SOTA, and POTA use. Latching relays mean essentially zero power draw once tuned, so an internal set of eight AA cells lasts about a year. It tunes from as little as 0.1 W - ideal for QRP - with 2,000 memories for instant retune and a wide 6-800 ohm range that handles up to a 10:1 mismatch. Optional Icom, Yaesu, and Kenwood interface cables add one-button tuning, and at about a pound it is easy to pack.
125 W maximum (100 W CW, 50 W digital), so it is barefoot-only - no amplifier. It is not weather-resistant, so it needs cover outdoors. There is no built-in power or SWR meter, just two status LEDs, and it needs a brief transmit carrier to start a tune. It has a single antenna port (no built-in switch). As with the rest of the LDG line, the company is small and its continuity has been questioned, so confirm support before buying.
A compact, low-drain external tuner that is a staple of portable HF stations. It tunes from QRP up to barefoot power, holds its match with no power thanks to latching relays, and runs a year on a set of AA cells - a natural fit for SOTA, POTA, and Field Day. The barefoot power ceiling and the need to keep it dry are the trade-offs, along with the usual LDG note about confirming current support.
The Z-100Plus is LDG's small, do-everything automatic tuner - the one that ends up in a go-bag. It is a switched-L tuner like the rest of the line, but built for portability: it runs from an internal pack of eight AA cells as readily as from a 12-volt supply, and because its relays latch, it draws essentially nothing once a match is set - under a microamp in standby - so a set of batteries lasts about a year of normal use.
It covers 1.8 to 54 MHz, matches 6 to 800 ohms (up to 3,200 with an external balun for ladder line), tunes a mismatch as bad as 10-to-1 down to near 1-to-1, and stores 2,000 settings so a return to a familiar frequency snaps to a match in a tenth of a second. The trick low-power operators care about is that it will tune on as little as a tenth of a watt, which suits QRP rigs that cannot put out the 5 or 10 watts many tuners need to start a cycle.
By itself it tunes by RF sensing - you key a brief carrier and it searches - but LDG sells interface cables that let it tune from the radio's own TUNE button: the IC-PAC for Icom's tuner-jack radios (which also feeds it power), Y-ACC cables for Yaesu, and a Kenwood cable. Power tops out at 125 watts on SSB and 100 on CW, dropping to 50 on the steady digital modes, so it is a barefoot tuner. It is also not weatherproof, so it stays inside or under cover in the field.
For SOTA, POTA, Field Day, or any station that wants a compact, low-drain external tuner, the Z-100Plus is a long-running favorite, descended from the switched-L design LDG introduced in the 1990s. It sits below the desktop AT-600ProII in power; for an Icom radio specifically the radio-powered IT-100 covers similar ground, and for a permanent outdoor install the feedpoint-mounted RT-100 is the relative that fights feedline loss. As with the rest of the LDG line, the company is small and its continuity has been questioned, so confirm support before buying.