This modulator amplifier for transmitters was found in a 1947 American book. The circuit uses an output with 4 tubes connected in parallel and in push-pull.
This amplifier, common in 1986, uses a hybrid integrated circuit that can offer some difficulty to obtain...
The basic idea of this 1989 circuit is to trigger a relay for a while when a call signal occurs on...
Although the system is experimental and should not be adopted by the arrival of digital radio, for those...