A transmitter and method for transmitting transponder or TCAS signals uses linear amplification to save on circuit component weight, cost and size while enabling precise amplification and control of the transmitted signal. The invention also relates to methods for controlling invertebrate pests by using these compounds and to plant propagation material and to agricultural and veterinary compositions comprising said compounds. More particularly, the plumb bob is rotatable relative to the body in both a first plane and a second plane, said planes being orthongonal to each other. The lever arm includes a cam surface. The bipolar transistor is constituted so as to be turned ON when an absolute value of the output voltage is lower than an absolute value of the power supply voltage, and so as to be turned OFF when the absolute value of the output voltage is higher than the absolute value of the power supply voltage.