ACOM 03AT | Automatic HF Antenna Tuning Unit

ACOM 03AT | Automatic HF Antenna Tuning Unit


The Automatic HF Antenna Tuning Unit (AATU) model ACOM03AT is a complete and self-contained unit for automatic matching of HF symmetrical antenna impedance to an unbalanced 50 Ohm output, that covers a continuous 1.8 to 16MHz frequency range and will withstand 200 to 2500W input power depending on the antenna SWR.


  • Easy to operate. The only operator obligation is to apply CW power while the matching process is fully automatic.
  • 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.
  • Remote matching - less losses in the feed line. The main (remote) 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.
  • Operates automatically with any transceiver without special signals - 10 to 100W CW for several seconds is the only requirement to perform automatic impedance matching.
  • Optical control link (up to 50m) between RCU and remote AATU 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 1-2kW.
  • Nonvolatile memory for 99 different user's tuning settings and selection of the power-on default.
  • 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.
  • 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).
  • Protected against atmospheric electricity via sphere spark gaps and a bleeder choke.
  • Options: Unbalanced output with 50 Ohm UHF(SO239A) connector; Control for the ACOM2000A HF linear amplifier and forACOM2000S automatic antenna selector; PC control via RS232 or RS422 serial port; Nonvolatile memory for user tunings.
  • Frequency coverage: 1.8   - 16MHz continuously; extensions and/or changes on request.
  • Maximum input power, PEP or CW, RTTY, FM, digital etc. (no mode limit), 100% duty cycle: at antenna SWR up to 3:1 - 2500W, 97% efficiency;

  - up to 5:1 - 1600W, 95% efficiency;
  - up to 10:1 - 1000W, 92% efficiency;
  - up to 20:1 - 500W, 85% efficiency;
  - up to 50:1 - 200W, 60% efficiency.

  • Input data:

  - nominal impedance: 50 Ohm unbalanced, connector type UHF/PTFE (SO239A);
  - input SWR during AUTO TUNE procedure: 1.7:1 max;
  - input SWR during OPERATE (matched): 1.5:1 max (1.2:1 typical)

  • Matching capability (antenna impedance range, SWR in respect to the nominal load impedance 200 Ohm balanced):

  - 1.8-16MHz: up to SWR 10:1 (20 Ohm - 2kOhm).
  - 3-14MHz: up to SWR 20:1 (10 Ohm - 4kOhm);
  - 6.5-12MHz: up to SWR 50:1 (4 Ohm - 10kOhm);

  • Nonvolatile memory for 99 different user's tuning settings and selection of the power-on default.
  • Power supply:

  - RCU: 230V, +10% / -25% (172-253V), 50-60Hz, 80VA;
  - Remote unit: fed by RCU output "24VAC/3A”

  • Size & weight (operating):

  - Remote unit: W 330mm (13”) x D 215mm (8.5”) x H 305mm (12”), 12kg (26.5 lbs.)
  - RCU: W 175mm (6.9”) x D 255mm (10”) x H 77mm (3”), 2,5kg (5.5 lbs.)

  • Operating environment:

  - Remote unit:
   - IP Protection Class: IP53 (NEMA Type 3);
   - temperature range: -40 to +65 degs.Celsius (-40 to 150 F);
   - relative humidity: up to 98% @ +40 degs.Celsius (104 F);
   - height: up to 3000m above sea level without output deterioration.
  - RCU:
   - temperature range: 0 to +50 degs.Celsius (32 to 122 F);
   - relative humidity: up to 95% @ +35 degs.Celsius (95 F).