Kenwood AT-250 Automatic Antenna Tuner

Technical Specifications

• Frequency Range: 160 through 10-meter amateur radio bands (1.8 MHz to 29.7 MHz).
• Matching Range: 20 to 150 Ohms (Impedance load matching capacity up to approximately 2.5:1 SWR).
• Maximum Power Capability: 100 Watts continuous RF input power.
• Auto-Tuning Power Limit: Requires reducing transceiver output to under 50 Watts during active auto-tuning sequences to ensure circuit protection.
• Antenna Ports: 4 discrete antenna outputs selected via an integrated rear relay switcher system.
• Interfacing Matrix: Standard 7-pin/8-pin control accessory cable linking directly to Kenwood matching transceivers for band data synchronization.
• Integrated Metering: Dual-movement cross-needle analog illumination panel tracking Forward RF Power, Reflected Power, and SWR.
• Power Source: 120V AC input or external 13.8V DC power lines.

Station Role

The Kenwood AT-250 automatic antenna tuner serves as the primary inline impedence matcher for the station's legacy HF equipment cluster. Positioned inline between the transceivers and multi-band antenna systems, it ensures optimal power transfer efficiency and keeps reflected SWR low across various operational frequencies to protect final transmission tubes.

History with Radio W8USR

The Kenwood AT-250 was added to the active W8USR workbench stack alongside our legacy Kenwood transceiver fleet. It has performed reliably over the years, handling quick frequency adjustments across the WARC and classic HF bands. It is preserved as a highly dependable automatic tuning module within our historical equipment archive.