RF Neulink NL5000-T - Manual (Page 14)

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The RF power module in the 10 watt UHF unit requires at least 12 volts to achieve 10 watts,
although voltages as high as 15 may be used. Since the module is powered directly from this
voltage, the supply should be “clean” and, preferably, regulated. The output power will vary with
supply voltage. The 7.5 volts required for the transmitter driver stages is developed by a regulator,
but since the current requirements are limited, the regulator is not a factor in determining the duty
cycle/key down limits.
5.3 DUTY CYCLE/KEY-DOWN LIMITATIONS
The major heat generating components within the module such as the RF power amplifier and
voltage regulator (if used) have maximum temperature limits that should not be exceeded. In
addition, the temperature within the module itself must be kept below the maximum temperature
of the reference oscillator. As a result, depending upon power, supply voltage, and temperature,
limits upon the average transmit duty cycle and the maximum continuous transmitter on time
exist. These limits are summarized below for operation in still air:
Temperature (°C) Duty Cycle (%) Key-Down Time (s)
w/o internal regulator:
3 watt RF output
25 100 30
60 15 5
6 watt RF output 25 80 30
60 10 5
10 watt RF output @ 13.5 V 25 30 15
60 5 5
w internal regulator
3 watt RF output 25 50 20
60 5 5
6 watt RF output 25 30 15
60 5 5
Blowing air across the unit and/or adding heat sinks can significantly improve the duty cycle/key-
down times, especially in units without the internal regulator.