Asimple series modulated AM QRP HF transmitter is essentially a basic, low-power radio for sending audio signals. Think of it as a starter kit for radio enthusiasts, perfect for those new to building transmitters or anyone interested in QRP (low-power) operation.
How it Works
This type of transmitter uses something calledamplitude modulation (AM). In simpler terms, AM works by varying the strength of the radio wave (the carrier signal) in time with your audio, like speech or music.
Key Features
- Low Power: These transmitters are designed to operate at very low power levels, making them ideal for QRP activities.
- Simple to Build: Consequently, their straightforward design makes them a popular choice for beginners who want to construct their own radio equipment.
- Series Modulator: Specifically, they use a series modulator to achieve the AM effect, which is a common and relatively simple method for this type of low-power transmission.
Therefore, if you’re looking for an easy-to-build, low-power AM transmitter for the high-frequency radio band, a simple series modulated AM QRP HF transmitter could be an excellent option.
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 – BD139 should have a heat sink to avoid thermal run away.
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