Acom 700S, Operating Manual, Page: 19 / 30

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4-3. Operation with an external antenna tuner
At antenna SWR over 1.5:1, it is advisable you use an external tuner. The ACOM 04AT Remote
Automatic Antenna Tuner is designed to work with the ACOM 700S. Use of other antenna tuners is not
recommended.
4-4. Automatic protection system
The control unit (S. 7-3(b)) keeps track of most amplifier analogue and logic signals in all modes.
Those are the receive/transmit control signal, the output relay contact state and switching times, the
RF drive frequency and drive power (the input power), the final transistors DC current and DC voltage
on the drains as well as, the gates bias voltage and the heat sink temperature, the main power supply
components temperature, the RF output forward and reflected power, and others. Some derivative
parameters, as the power gain, the SWR, the heat power dissipated by the final transistors dynamically
and others, are watched too.
In the event a parameter maximum is exceeded, the amplifier will assess the risk and will trigger one
of the three levels of protection, as described in items (a) to (c) below. Every event is accompanied by
a warning text on the screen (Fig. 4-1). A sound alarm will be also produced, if set on in the “USER
PREFERENCES”– fig. 5-4.
Fig. 4-1 – Appearance of an alarm message
a) The first protection level is WARNING. When a value watched by the control unit approaches
the protection threshold, the transmission is not interrupted, but a message appears – for
example “Drive Power too High”, “Drain Current too High”, or another – Fig. 4-1.
You can continue to transmit in these conditions, but you have to take some measures, for example, to
reduce a bit the drive power from the transceiver. The warnings remain on the screen for at least three
seconds so that they can be read through and will disappear after the reason has dropped off.
b) The second protection level is a SOFT FAULT – when a value exceedsed the safe level,
but does not put the amplifier in a danger of a failure.