Duty Cycle; T/R Control Or Switching; Power Output - Mirage B 1018 G User Manual

Maximum power output for good linearity is 110 watts PEP, as indicated on a properly working
PEP-reading meter.
In AM operation, carrier output power is normally 25% or more of the peak envelope power as
indicated on a true peak-reading meter. Unmodulated carrier power should not exceed 25 watts;
peak envelope power on AM should not exceed 100 watts or so.

4.3 DUTY CYCLE

The duty cycle of this amplifier is limited by temperature considerations. In normal AM or SSB
operation, the duty-cycle is set by ambient temperature, mounting position, operating power, and
airflow. Temperature and mounting concerns are detailed in section 1.0. Driving-power
concerns are detailed in section 4.2.
The maximum PEAK amplifier output power on SSB and AM is 110 watts PEP. At the
maximum power output of 110 watts, this amplifier will normally provide a 100% duty cycle
without overheating.
If possible, especially if cooling might be marginal and there is no external air blowing across the
heatsink, mount the amplifier with heatsink fins vertical. This allows natural convection to
circulate air. See section 1.0 for details.
Warning, the safe maximum temperature of the heatsink is 140°F. If the heatsink
feels too hot to hold, it is almost certainly too hot for safe operation.

4.4 T/R CONTROL OR SWITCHING

This amplifier has an internal RF sensing system that turns off the pre-amplifier and places it in
the transmit mode. A front-panel MODE switch activates an internal hang-delay timer for SSB
(or CW) operation. This hang-time allows the relays to remain energized without input power for
a few seconds.
The hang-time is controlled by R8, located at the front and center of the board behind the MODE
switch. Delay is normally set for 1 second at the factory.

4.5 POWER OUTPUT

The maximum power output for clean linear SSB service is 110 watts PEP. Antenna SWR
should be as low as possible. The 13.8-volt 30-ampere power source must not have hum or
ripple. The voltage should have less than 0.2 volts sag under full-load for best linearity.
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