Acom AOM 04AT User Manual page 11

User's Manual | ACOM 04AT | Remote Automatic Antenna Tuner and Switch
The tuner matches all load impedances presenting a SWR below 3:1, regardless of phase angle, in a continuous
frequency range of 1.8-30 MHz and 50-54 MHz. In many cases, the tuner will match loads with higher SWR (up
to 10:1) as well, however a reduction in power may be necessary if the protective functions of the tuner
activate due to high values of SWR, current, voltage, forward or reflected power at the antenna output.
Provided the SWR of the feedline/antenna system is up to 3:1, the tuner can handle input power levels up to
1200 W (PEP, mean or continuous carrier), regardless of the operating communication mode. For
feedline/antenna system SWRs between 3:1 and 10:1, the maximum permissible power at the tuner input is
gradually reduced down to 200 W at SWR=10:1 (see
Table 8-1 | Maximum input power of the tuner as function
), allowing for operation within tuner component specifications.
of the antenna SWR
The tuner can be installed both in the shack and in a remote location, e.g., in a separate room, in a sheltered
location outdoors or even out in the open, close to the antennas, so that any feedlines from the unit to the
antennas, working in mismatched conditions, are kept as short as practically possible to avoid unnecessary
losses.
Generally, a remote installation of the tuner is preferable to a local one, because it reduces RF losses in most
of the feedline's length. Thanks to the built-in automatic antenna switch, a significant reduction in both
installation effort and required cable length can be achieved (up to three times the feedline length with four
antennas and in-shack tuner installation).
A single cable connects the tuner to the radio station - the main coaxial feedline, which is often already pre-
installed. Tuner power supply, control and RF signals are combined on the feedline, easing remote
installation, lowering costs, and uncluttering the shack.
Provided a low loss hi-quality cable is used (e.g., RG213), the distance between the tuner and the shack can
be up to 100 m (330 ft). However, the length of the cable should be kept at minimum to avoid any
unnecessary losses, which exist in any cable even in matched conditions.
The wide operating temperature range of the tuner (-40 to +65 °C), the single cable to the shack, and the
included accessories - all make for an easy outdoor installation.
However, if you have a choice of installation locations, you should always prefer one that is sheltered from
the elements. It will prolong the operational life of the tuner and reduce material wear.
Regardless the choice of installation location, the operator is able to control and monitor the tuner's work
via the amplifier front panel using simplified and intuitive menus in the original style of the ACOM transistor
amplifier series.
October 2023 S e c t i o n GENERAL INFORMATION | Page 11 of 88