Sunday, July 6, 2014

A small two stage transistor AM transmitter

by Free Radio Beacon

This is two-stage transistor AM transmitter for the shortwave band, which gives about 1 watt in output. You can use a 2N2219 or a 2N3553 in the final stage. The output with a 2N3553 is aprox. 1.8 watt @ 12 Volt. The transmitter seems to give more output when you use 7 turns instead of 4 turns in the secondary section of T1 (the coil between oscillator and final stage). It will work fine between 6 and 8 MHz. Try with different (power) transformers to modulate the transmitter in Amplitude Modulation. You have to do experiments to find a suitable modulation transformer to produce a good Amplitude Modulation.
Also test with different transistors in the final stage, but be careful to not blow up the rig.

  • BD135 - gives 1.7 watt output @ 13.8 volt
  • C2314 - gives 2.4 watt output @ 13.8 volt
  • BLY88C - gives 3 watt output @ 13.8 volt


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