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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-powcr
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.
4.4 T/R CONTROL OR SWITCHING
This amplifier has an internal RF sensing system that places it in the transmit mode when RF is
applied.
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.
4.6 ANTENNAS AND FEEDLINES
Any antenna and 50-ohm feedline can be used, providing it presents less than 2:1 SWR to this
amplifier. Linearity and splatter will be better controlled if SWR is as low as possible, with a 1:1
SWR ratio (unity SWR) being ideal.
Be sure to use proper lightning protection techniques when using this amplifier for home or fixed
operation.
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