Acom Automatic antenna tuner


Acom Tuner 04AT

The Acom 04AT is an automatic antenna tuner, which has been specifically designed for operation with the Acom Transistor amplifiers. In such a combination, both the amplifier and the tuner form a perfect team for very comfortable automated operation at high power.

The tuner ACOM-04AT is either installed locally in the shack. or remotely at the antennas, in a distance of up to 100 m. This reduces cable losses over the long feed line, because only the antenna nad the relatively short local feed line is tuned. Control, HF signal and power supply is entirely handled via one coaxial cable, no firther connection between amp and tuner is required. All Acom transistor amplifiers can serve as a power feed and controller for the tuner, for example the Acom 1200S, the Acom 600S etc. The possible frequency range covers the entire shortwave band from 1.8 to 30 MHz and the 6m band from 50 to 54 MHz. The maximum power is - dependig on antenna matching - up to 1200 W.

A maximum of four antennas can be connected to the tuner. The selection of one antenna is done either manually from the controls on the amplifier, or automatically by the operating frequency. All inputs are protected with two circuits against static discharge and nearby lightning strikes. All antenna inputs can be switched to "bypass" in case an antenna should be operated directly, without tuner. Tuning of the ACOM-04AT happens automatically or by manual command. This process takes a maximum of 5 seconds, usually 2 t o3 seconds, and much faster when a once used frequency/antenna combination is used again. In this case the settings are recalled from 1000 storage positions. The storage is in NVRAM, so all settings remains available even when powered down. These settings can even be exported to a computer and later restored if required. If the amplifier and the transceiver are connected via a CAT cable (and thus the amp can monitor the operating frequency) the tuner always follows the frequency and selects antenna and matching, even when the transmitter is not engaged. This CAT connection is optional, it is not required for fully automated operation.

The Tuner offers various protection mechanisms to protect the amplifier and itself. Monitored parameters are supply voltage, voltage polarity, excessive HF voltage, excessive HF current, reflected power, input power, temperature andm uch more. In case of a bad SWR the tuner 04AT signals this error to the amplifier which then can reduce the transmitted power. At full power (1200W PEP or CW) a maximum mismatch of up to 3:1 can be handled. In some cases a mismatch of up to 10:1 can be handled, but in those cases the transmitted power must be reduced, see table below. While tuning is in process the SWR towards the amplifier never exceeds 2:1, after tuning the SWR is usually 1.5:1 or better. The current operating state of the tuner is shown on the amplifier display, so you can easily monitor your entire transmitter chain from amplifier over the tuner to the antennas.

Technical Data ACOM-04AT Tuner
Frequency Range 1.8 – 30 & 50 – 54 MHz
SWR Range 1:1 – 3:1 [1]
Max. Power at SWR 3:1 1200 W [2]
Min. TX power for SWR measurement 25 W ± 3dB
Impedance 50 Ω
Connectors Antenna 4 × PL jack
Connector Final Amp 1 × PL jack
Maximum cable length,Longuer maximale du câble PA↔Tuner 100 m [3]
Dimensions 345 × 250 × 190 mm (W x D x H)
Weight 4.2 kg
Protection class IP 53 (NEMA Type 3)
Temperature range -40 – +65 °C
Max. Humidty 98% @ +40 °C

[1] Operation is possible in some case with a mismatch of up to 10:1, at reduced power.

[2] Max. allowed power at SWR:

SWR ≤ 3:1 3.5:1 * 4:1 * 5:1 * 7:1 * 10:1 *
Pin [W] 1200 900 700 500 300 200

[*] Only if tuning at an SWR worse than 3:1 is possble at all. Operation at an SWR over 10:1 is not permitted, even when the tuner finds a match.

[3] Max. length of cable at an cable quality of RG-213 or better.

  • Included in shipment
  • ACOM 04AT Tuner
  • Weather proof hood
  • Mounting for desk
  • Mounting for wall installation
  • Mounting for mast installation
  • Printed manual (englisch)
Order No.
ACOM-04AT Acom Remote Antenna Tuner 04AT 1249.00 € Add to shopping cart New Ordered only on customer request, delay at c. 60 days.
Info freight charges


Automatic tuner ACOM-03AT Automatic tuner ACOM-03AT

The ACOM 03AT is a complete automatic tundr for remote mounting directly to the antenna. The tuner fits symmetric antennas on a 50 Ω unbalanced throughout the range of 1.8 - 16MHz to. Depending on antenna matching the maximum power is beetween 200 and 2500W.

  • To start the tuning process, you simple send a signal to the tuner in CW. The tuning process will start automatically..
  • While tuning your transmitter is protected against mismatches by a automatically attenuator switch. After tuning, it is switched off again. In addition, the tuner and the relay to "hot-switching", excessive antenna voltage, overheating, etc. protected.
  • Through remote operation, you have less losses in the supply line. The antenna is tuned directly to the outside unit and thus is not a high SWR on the feed line.
  • Operates automatically with any transceiver without special requirements. Just a CW signal with 10 to 100 W for a few seconds and the automatic adjustment is carried out.
  • The connection between the controller unnd outdoor unit can be made up to a length of 50m with fiber optic cables. This avoids interference of the controller with high transmission power.
  • Nonvolatile memory for 99 different user preferences and the selection of the power on mode.
  • 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).
  • Options: Unbalanced output with 50 Ohm UHF(SO239A) connector; Control for the ACOM2000A HF linear amplifier and for ACOM2000S automatic antenna selector; PC control via RS232 or RS422 serial port; Nonvolatile memory for user tunings.
Order No.
ACOM-03AT ACOM-03AT Automatic antenna tuner 18999.00 € Add to shopping cart Ordered only on customer request, down payment required, delay at c. 60 days.
Info freight charges
Due to several requests: Yes, the price for this antenna switch is not a joke!