FM Wireless Transmitter Module (+ Microphone)

Description
DH-Radio transmitter module with microphone is an FM frequency band transmitter. The green component on the core board is an adjustable capacitor (Change the adjustable capacitor can change the transmission frequency)
For testing, you can use this module as the transmitter and your mobile phone as the receiver. 

Features
Frequency range: 88MHZ ~ 108MHZ
Default Frequency: 100MHz
Operating voltage: 0.7V ~ 9V
Transmission distance: 50 ~ 100 meters (at 9V , the use of 70 cm Antenna, open space)
The relationship between the operating voltage (V) and the supply current (mA) and the transmitted power (dBm) is as follows:
9V    ,   24mA    , 10.2dBm
8V    ,   21mA    , 9.5dBm
7V    ,   19mA    , 8.5dBm
6V    ,   17mA    , 7.1dBm
5V    ,   14mA    , 6.1dBm
4V    ,   12mA    , 4.5dBm
3V    ,   9mA      , 2.2dBm
2V    ,   6mA      , -1dBm
1.5V ,   4.2mA   , -4dBm
1V    ,   2.4mA   , -9dBm
0.7V ,   0.9mA   , -20dBm