Note
The AT-250 is an automatic antenna tuner capable of handling 100W of continuous input power. It is engineered to automatically match antenna loads between 20 and 150 ohms, corresponding to a Standing Wave Ratio (SWR) of approximately 2.5:1. The unit features multiple antenna outputs and dual-power compatibility, making it suitable for both home and mobile stations.
The AT-250 was designed as a dedicated companion for the TS-430S. While the tuner can be used with other Kenwood models like the TS-140S, TS-440S, and TS-530S, it features specific integration with the TS-430 series.
In its review of the TS-430S system, QST highlighted the AT-250 as the recommended automatic solution for operators seeking a matching station footprint with high-speed, motorized tuning.
The tuner was also marketed as a high-performance alternative for the TS-440S for operators who required 160-meter coverage, as the internal tuner in the TS-440S (the AT-440) was limited to 80–10 meters.
Its arrival marked a shift toward fully automated station integration. While earlier tuners (like the AT-230) were manual, the AT-250 utilized microprocessor control to match the band switching of the then-new TS-430S.
Key Features
– Comprehensive Band Coverage: 1.8 MHz through 28 MHz, including the WARC bands.
– Automatic Band Selection: When used with the Kenwood TS-430 transceiver, the tuner automatically selects the correct operating band.
– Dual Power Capability: Can be powered by either AC (120V, 220V, or 240V) or 13.8V DC.
– Integrated Power-SWR Meter: Features a built-in meter that calculates SWR automatically and displays transmit power on 20W or 200W scales.
- Four-Antenna Support: Equipped with four coaxial antenna jacks, allowing users to switch between multiple antennas via a front-panel control.
– Through Mode: In normal operation with the RX switch set to "OUT," the tuner remains "through," allowing the signal to pass directly unless tuning is engaged.
Specifications
– Frequency Range: 1.8 MHz to 29.7 MHz
– Input Impedance: 50 ohms unbalanced
– Output Impedance: 20 to 150 ohms unbalanced
– Insertion Loss: 0.8 dB or less
– Power Handling: 100W continuous; 200W PEP
– Tuning Accuracy: Motors stop when SWR is 1.2:1 or less
– Min. Activation Power: 3 Watts
– Max. Tuning Time: Within 15 seconds
Power Consumption: 15W (AC) or 13.8V DC at 600 mA
