A simple series modulated AM QRP HF transmitter is a type of radio transmitter that uses amplitude modulation (AM) to transmit audio signals over a high frequency (HF) radio band. It is designed to be low-power and simple to construct, making it a good choice for beginners or those who want to build a QRP (low-power) transmitter. This type of transmitter uses a series modulator to modulate the amplitude of the RF carrier signal.Series modulated AM transmitters are typically low-power transmitters, and are often used in QRP (low-power) applications. They are also relatively simple to construct, making them a good choice for beginners.
L1 – for 3.9 MHz, 40 turns. for 7.2 MHz, 23 turns. AWG #30 on a T50-2 core.
L2 – 110uH inductor, 1 watt
L3 – 12 turns on T50-2 core 22 SWG wire
Q2 should have a heat sink to avoid thermal run away.
Related circuits