Turning amplifier on and off
Transmit power amplifier and receiver preamplifier functions are independent on
each other. They can be toggled on/off by pressing respective pushbuttons: RX LNA
and TX PA. When function is enabled, LED associated with pushbutton is lit.
Amplifier is completely off, when both LEDs are dark.
Changing power level
Transmit power amplifier is equipped with Automatic Level Control loop (ALC).
Preset power is adjustable is 8 steps: 10W,20W,30W,40W
,
50W,60W,70W,80W. First
press of SET POWER button enters power setting mode. Multifunction display bar
blinks, showing preset power level. First press of SET POWER button, doesn't
change the level, but displays actual setting. Subsequent pressing of SET POWER
button change power setting. Amplifier exits power setting mode if SET POWER
button is not pressed again within 2 seconds.
Automatic Level Control is of saturated nonlinear type, only suitable for FM
modulation. While using amplifier with AM/SSB modulations, set ALC threshold to
maximum power (50W), then adjust transceiver power to yield appropriate power
displayed on bargraph. For AM modulation, carrier power should not exceed 10-15W,
to accomodate modulation peaks without distortion.
In case of SSB modulation, observe bargraph which is of PEP type, keeping 50W
LED lit only ocassionally.
Turning SSB mode on/off
The SSB ON button toggles SSB mode on/off, actual state indicated by associated
LED. When SSB mode is enabled, carrier sensing algorithm, time delays, power
meter bar behaviour are changed to address modulation properties. There is no
difference in power amplifier biasing itself, since this modern desing is inherently
linear, unlike elder bipolar transistor based designs.
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