DR4100 Description
The TX IN pin is connected to the transmitter TXMOD pin through a 4.7 K resistor on the circuit board. Additional series resistance will often be required between the modulation source and the TX IN pin, depending on the desired output power and peak modulation voltage (3.3 K typical for a peak modulation voltage of 3 volts). Saturated output power requires about 450 µA of drive current.