There is an LED terminal to indicate that the signal is being received.




* A 4.2 V power supply is used for the electret condenser microphone. The recommended value for R1 is 2 kohm with a 4.2 V supply. 
* If the input level is too high, insert a VR or simply insert a resistor at Mic.IN terminal in serial. (The level is lowered by -6 dB with 5 kohm, and by -10 dB with 10 kohm ignoring impedance of the microphone.) 
* If the level is insufficient, a microphone amplifier is required between the microphone and the WA-TX-03-R