The Acom ATU04 Automatic Antenna Tuner is designed for installation in a shack, under a shed, or in open spaces. It can be placed up to 100 meters away from the amplifier. The tuner is powered and controlled directly from the ACOM solid state HF+6m amplifiers through the RF output cable, eliminating additional power or control cables. It provides automatic or manual antenna change and automatic antenna impedance matching to the ACOM amplifiers, all controlled from the amplifier front panel and transceiver CAT. The tuner guards against excessive impedance mismatch during the tuning process. It operates with two types of tunings: full tuning and fast tuning. The operator initiates full tuning and is 100% automated, while fast tuning retrieves user-tuning patterns from nonvolatile memory. The tuner offers four typical antenna types: Regular, Sharp, Wide, and Fixed-frequency, allowing the operator to adapt the frequency segment width to the specific antenna bandwidth. BYPASS mode is also available. Antennas are displayed with a number, type, and user-editable name on the ACOM amplifiers screen, with tunings availability presented by a graphic scale. The tuner provides a range of antenna- and tuner-related information on the amplifier screen, including menus for ATU SERVICE, ATU MEASURE, ATU TUNINGS LOOKUP/ERASE, and a Resource-estimate function. It also offers a tuning "age" warning to alert the user when using outdated tunings. The user can archive all tunings in a computer file and upload archived files to the tuner's nonvolatile memory through the amplifier's RS232 port.

The tuner is equipped with various protections, including voltage, polarity, RF voltage, RF current, reflected power, tuning power, input power, and relay switching protections. It is also protected against static electricity and close lightning strikes. The tuner has a frequency coverage of 1.8 to 30MHz and 50 to 54MHz, with continuous coverage from 30 to 50MHz available upon request. It can match all impedances with 50 Ohm-SWR between 1:1 and 3:1, with power limitations for higher-SWR impedances. The RF input characteristics include a nominal impedance of 50-Ohm unbalanced and an input SWR below 2:1 during full tuning. The antenna output characteristics include a nominal impedance of 50-Ohm unbalanced, four outputs, and an antenna SWR between 1:1 and 3:1 for 100% matching at full power. The entire tuning duration is less than 5 seconds below 10MHz and less than 3 seconds above 10MHz. The RF input power required during full tuning is 25W +3/-3 dB. The tuner is powered and controlled through the RF-output coaxial cable, with a power supply of +26VDC and up to 25W consumption. The control data is transmitted using an FSK modem at 60 kHz. The maximum length for the coaxial cable is 100 meters for cable type RG-213. The tuner is compact, measuring 345mm in width, 250mm in depth, and 190mm in height, with a mass of 4.2kg. It is designed to withstand various operating environments, with weather protection rated at IP 53, a temperature range of -40 to +65 degrees C, humidity tolerance of up to 98% at +40 degrees C, and the ability to operate at heights up to 3050 meters without deterioration in performance.

It provides automatic or manual antenna change and automatic antenna impedance matching to the ACOM solid-state HF + 6m amplifiers, controlled entirely from the amplifier front panel and your transceiver CAT.