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.
 Operation is possible in some case with a mismatch of up to 10:1, at reduced power.
 Max. allowed power at SWR:
[*] 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.
 Max. length of cable at an cable quality of RG-213 or better.