| The above diagram shows the components of an automatically band changing SO2R setup.
The RF paths are in red, and the wiring busses are in black arrows. The represent cables
that interconnect the radios, automatic band decoders, the antenna switch and bandpass
filter switch.
The output of the SixPak can have additional high power filters put in place. A
modern station will have 1/4 WL stubs teed to the output of the SixPak or may also may
include 2 kW low pass filters to severely cut
down harmonics out of the amplifiers or a combination of both.
In all cases the RF cables inside the radio shack should be double shielded types to
keep RF leakage to a minimum.
The use of bandpass filters and high power filters allows the SO2R operator can
achieve a high degree of suppression of hash, phase noise, harmonics, and receiver
de-sense. Without these filters not only will the operator not be able to hear on the
other bands but he risks damaging the front ends of his receivers from RF power coupled
from the antennas.
By doing this you may expect to achieve such a high level of isolation between your
antennas that you may use multiple antennas on the same tower, use quads on adjacent
bands successfully, or use a tribander on different bands (of course you will need
separate feeds for quads and tribanders).
Now we need to control the headphone audio, PTT, microphone, footswitch, and PC
interface. These circuits are easily managed and controlled by the PC with the
Array Solutions SO2R Master controller, or can be built by the user. The diagram below
shows what a complete interface looks like.
Note that the SO2R Master was discontinued several years ago, since it was
controlled by the LPT port of a PC which is hard to find in modern operating
systems.
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