An FM transmitter overvoltage protection circuit diagram

The exciter of the FM302E-I FM transmitter adopts the HPB-1210 motherboard of Japan's NEC Company. Direct frequency modulation of the carrier uses phase-locked frequency stabilization and frequency synthesis technology. The front-stage power amplifier (BLF-177 field effect tube) is directly driven by the exciter, with a maximum output power of 150W. It passes through the circulator to the final stage and serves as the driving stage for the final tube power amplifier. The integrated power supply and power amplifier tube are relatively expensive and the losses are very high. Therefore, it is necessary to add an overvoltage protection circuit to the power amplifier tube of this level, especially since our station is located on a high mountain. During the thunderstorm season in summer, lightning often enters the power line and burns out the transmitting equipment. Coupled with an overvoltage protection circuit, it ensures safe and high-quality broadcasting, reduces broadcast suspension rates, and can save a lot of money.

The FM transmitter modulates the audio signal and high-frequency carrier wave into an FM wave, so that the frequency of the high-frequency carrier wave changes with the audio signal, and then amplifies, excites, power amplifiers and a series of impedance matching the generated high-frequency signal. , a device that outputs signals to the antenna and sends them out.

Here we introduce to you the overvoltage protection circuit diagram of an FM transmitter.