ACOM 03AT | Automatic HF Antenna Tuner

ACOM 03AT | Automatic HF Antenna Tuner

The Automatic HF Antenna Tuner (AATU) model ACOM 03AT is a complete and self-contained device for automatic matching of HF symmetrical antenna impedance to an unbalanced 50 Ohm output, that covers a continuous 1.8 to 16 MHz frequency range and will withstand 200 to 2500 W input power depending on the antenna SWR. ACOM 03AT consists of two modules - A Remote Tuner Unit and Remote Control Unit (RCU).

Easy to operate
The only operator obligation is to apply CW power while the matching process is fully automatic.

Remote matching
Remote matching - less losses in the feed line. The remote tuner unit design complies outdoor-installation requirements. This permits you to locate it closely to the antenna feed-points, thus considerably reducing the high-SWR RF path length.

Automatic operation
Operates automatically with any transceiver without special signals - 10 to 100 W CW for several seconds is the only requirement to perform automatic impedance matching.

Optical control link
Optical control link (up to 50 m) between RCU and remote tuner unit. This avoids erratic control at a strong electromagnetic RF field which is the typical case in the near-field zone of an antenna when emitting 1-2 kW.

BYPASS function
Features BYPASS function, performed by default also when powered off, where the effect of the inductors and capacitors on the impedance is excluded for broadband operation (the balun transformer still inline).

Resource-estimate function
Resource-estimate function (STATUS) giving the percentage of inductors and capacitors involved to achieve a match. This offers a possibility for monitoring the condition of the RF path and the antenna, thus to forewarn possible problems.

Protection against atmospheric electricity
Protected against atmospheric electricity via sphere spark gaps and a bleeder choke.

Guards your transmitter during the tuning process against excessive impedance mismatch via inserting a powerful attenuator at the input, and removing it after that. Protected against relays "hot" switching, excessive antenna voltage, overheating, etc.

Non-volatile memory
Non-volatile memory for 99 different user's tuning settings and selection of the power-on default.


  • Unbalanced output with 50 Ohm UHF(SO-239A) connector.

The User's Manual is available as a PDF file only. The latest version of the User's Manual is available under the Download tab (see above).

Frequency coverage

  • Continuous 1.8 to 16 MHz;
  • Extensions and changes on request;

Maximum Allowed Input Power (PEP or CW, RTTY, FM, digital, etc. (without mode limitations, 100% duty cycle)

  • At antenna SWR below 3: 2500 W, 97% efficiency;
  • At antenna SWR between 3 and 5: 1600 W, 95% efficiency;
  • At antenna SWR between 5 and 10: 1000 W, 92% efficiency;
  • At antenna SWR between 10 and 20: 500 W, 85% efficiency;
  • At antenna SWR between 20 and 50: 200 W, 60% efficiency;
  • At antenna SWR above 50: 100 W;

RF Input Characteristics

  • Rated impedance: 50 Ohm unbalanced;
  • Input connector type: UHF/PTFE (SO-239A);
  • Input SWR during AUTO TUNE procedure: 1.7 max.;
  • Input SWR during OPERATE (matched): 1.5 max. (1.2 typically);

Antenna Impedance Matching capability (Antenna impedance range, SWR in respect to the nominal load impedance 200 Ohm balanced)

  • 1.8 - 16 MHz: Up to SWR 10 (20 Ohm - 2 kOhm);
  • 3 - 14 MHz: Up to SWR 20 (10 Ohm - 4 kOhm);
  • 6.5 - 12 MHz: Up to SWR 50 (4 Ohm - 10 kOhm);

Non-volatile memory

  • Non-volatile memory for 99 different user's tuning settings and selection of the power-on default;

Power Supply

  • Remote Tuner Unit: Fed by RCU output "24VAC/3A OUT";
  • Remote Control Unit: 230 VAC, +10/-25% (172-253 VAC), 50-60 Hz, 80 VA;

Size & Weight (Operating, excluding connected cables and opened tilt foot bar on RCU)

  • Remote Tuner Unit, WxDxH: 330x215x305 mm, 12.0 kg (13.0x8.5x12.0 inches, 26.5 lbs.);
  • Remote Control Unit, WxDxH: 175x255x77 mm, 2.5 kg (6.9x10.1x3.1 inches, 5.5 lbs.);

Shipping Size & Weight (including both units)

  • WxDxH: Approx. 600x420x430 mm, 23.0 kg (23.7x16.6x17.0 inches, 50.8 lbs.);
  • Please, contact us for shipment details;

Operating Environments

  • Remote Tuner Unit
    • Weather protection: IP 53 (NEMA type 3);
    • Temperature range: -40 to +65 degrees Celsius (-40 degrees F to 149 degrees F);
    • Relative air humidity: Up to 98% @ +40 degrees Celsius (104 degrees F);
    • Height above sea level: Up to 3050 m (10000 ft) without output deterioration.
  • Remote Control Unit
    • Temperature range: 0 to +50 degrees Celsius (32 degrees F to 122 degrees F);
    • Relative air humidity: Up to 95% @ +35 degrees Celsius (95 degrees F).

There is one individual purchase option available:

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