Kenwood AT-130
A compact HF antenna tuner that pairs a coupler, SWR meter, and antenna switch in a 1.6-kilogram box built for the ham shack or the field.
Overview
The AT-130 is a high-performance HF antenna tuner, and Kenwood's own documentation describes it as a modification of the popular AT-200. It is a repackaging of an established circuit into something smaller and lighter, not a clean-sheet design. It covers eight amateur bands from 3.5 to 29.7 MHz and weighs approximately 1.6 kg (3.5 lbs). Dimensions are 60 mm high, 152 mm wide, and 159 mm deep - roughly 2-3/8 by 6 by 6-1/4 inches. Kenwood positions it for the home station but also for mobile or field operation, and ships a mounting bracket to back that up.
Three functions share the chassis: an antenna coupler, an SWR meter, and an antenna switch. The coupler takes a 50-ohm input and transforms it to an output impedance of 20 to 300 ohms, unbalanced. Through power is rated at 150 watts maximum, but the manual specifies 120 W on the 3.5 MHz band, so read that part carefully. Insertion loss is quoted at less than 0.5 dB at optimum match. That's the number that counts in daily use, since a tuner that swallows signal is a tuner you stop using.
The SWR meter spans the same 3.5 to 29.7 MHz range and handles up to 150 W, with a measurable range of 1.0:1 to 10:1. It needs just 2 W to give a reading, so it works for low-power operation too. The meter operates in both THROUGH and MATCHING modes, and the panel meter can be illuminated from an external power source, which helps in a dark mobile installation or a field position at night. Matching or through operation is selected by a band switch rather than a separate control, so the front panel stays sparse.
Connections are standard for the era: UHF-type connectors at 50 ohms for both the INPUT and ANT jacks, plus a wing nut and stud for ground. Nothing exotic, nothing proprietary. Kenwood also notes that the antenna matching circuit doubles as a band-pass filter, which helps reduce TVI - television interference. For operators running HF in densely populated areas, that side benefit was often as valuable as the matching itself.
Kenwood's instruction manual carries the usual service guidance. The unit is factory aligned and tested before shipment, service should go through an authorized dealer or Trio-Kenwood, and the complete unit should be shipped in its original boxes rather than as loose sub-assemblies or circuit boards. The manual also specifies the dial lamp as part number B30-9996-00, rated 12V at 40 mA. Lamp replacement is one of the few maintenance tasks an owner can reasonably handle. The procedure calls for removing the top cover, noting the lead positions on the S meter and lamp PCB, removing the meter bracket and two brass Philips screws, then swinging the board's rear edge up and out.
Kenwood's documentation is inconsistent on range. The feature list says the AT-130 is designed for amateur bands between 3.5 MHz and 30 MHz, while the specification section quotes 3.5 to 29.7 MHz. Treat the spec sheet figure as the operating range and the 30 MHz reference as rounding. The manual also notes that circuits and specifications are subject to change for improvement without notice, so late-production units may differ in small ways from early documentation.
Based on available documentation, the AT-130 is not a wide-range universal tuner. Its output impedance window of 20 to 300 ohms is a real constraint, and operators hoping to match a random longwire with a wild impedance swing should know that going in. It is a compact coupler for amateur bands, with a meter that reads down to 2 W and a through-power ceiling of 150 W - or 120 W on 80 meters.
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