The Mitsubishi MD003 is a solid-state RF switch capable of switching up to 5 watts in the frequency range 800 - 940 MHz. Looking at the module, with the label facing you, pin 1 is on the left hand side. Connections are as follows : 1 2 3 4 5 6 7 GND RX GND BIAS ANT GND TX With NO current into the BIAS pin (4) the ANT is connected to RX with a loss of 1 - 1.5 dB. When you supply a current of 50 mA into the bias pin (through a series resistor) the ANT is connected to TX with a loss of 0.5 - 0.7 dB. With a 100 mA bias, it can handle 12 watts max. T-R isolation is 30 - 35 dB.