The ACOM 20AT is an indoor automatic tuner that was specially designed for use with the Acom 2020S transistor PA. In such a combination, the power amplifier and tuner form a perfect team for very convenient automatic operation at high power.

The ACOM 20AT tuner can be operated either locally in the shack or remotely at a distance of up to 100 meters in closed rooms. This reduces losses, because only the antenna and its relatively short feed line from the tuner itself are tuned, not the feed line to the antenna. The control and supply is done completely via a coaxial cable, no further line to the tuner is necessary. The frequency range covers the whole shortwave from 1.8 to 30 MHz as well as the 6-m-band from 50 - 54 MHz. Depending on the matching of the antenna, maximum power levels of up to 1500 W are possible.

A maximum of four antennas can be connected to the tuner. The selection of the respective antenna is done either manually via the control on the PA or automatically based on the frequency. All inputs are statically double protected against charge and lightning nearby. The antenna connections can also be switched to “bypass” to use an antenna directly, without a tuner. The tuning process of the ACOM 20AT tuner is automatic and transparent to the user. This takes a maximum of 5 seconds and usually no longer than 2 - 3 seconds. Once found, the tuning settings are stored permanently. For stored antennas/frequency combinations, the tuning process takes less than half a second. The settings stored in this way can also be exported to a computer and reimported later. Up to 1000 memory positions are available. If the PA and the transceiver are connected via a CAT interface (and the PA can always track the operating frequency), the tuner follows the set frequency and also selects matching and antenna connection without the need for transmission. This CAT connection is optional and is not required for fully automatic operation.

The tuner offers various protective circuits and thus also protects the output stage. It checks the supply voltage, polarity, excessive RF voltage, RF current, reflected power, input power, temperature and much more. If the SWR is too poor, the tuner signals the error condition and the PA regulates the transmission power down. At full power, mismatches of up to 3:1 can be compensated. Even less well-matched antennas can be used with an SWR of up to 10:1 in individual cases, but then operation is only possible at a greatly reduced power. During the tuning process, the input SWR of the 20AT tuner never rises above 2:1, and as soon as a match is found, the input SWR to the power amplifier is no higher than 1.5:1. The respective operating status of the tuner is shown on the display of the PA, so you always have full control over the entire antenna system, including the power amplifier.