A suitable transmitter was offered for numerous receivers used by radio amateurs. A „RECEIVE - TRANSMIT“ switch on the receiver switches off or short-circuits the antenna input to protect the highly sensitive input stage when the transmitter is in operation.
In early wireless equipment, the receiver and transmitter were usually built in two separate units, in modern times, both are combined in one set, in a transceiver. As space requirements and power supply don't allow high power output stages in small portable sets, quite often a separate RF amplifier with a separate heavy power supply is used, when high transmitter output is needed.