RF Neulink NL5000 Rev B0 - Manual (Page 12)

NL5000 User Manual Rev B0 11
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-DownTime (s)
With internal regulator 60 5 5
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.