Скачать или смотреть AMT-MW207 AM medium wave transmitter test on 1812 Overture (Tchaikovsky)

I used a Wellbrook ALA1530LN antenna during the test and the transmitter was put on the loop amplifer. Ferrite rod and loop antenna were aligned to improve reception. Transmission range is less 1 meter (there is no antenna). Carrier is visible up to 10 meters on the computer. Modulation quality is better on low frequency. On the last 200 kHz sidebands are completely asymmetrical and index modulation must be reduce to prevent overmodulation.

The coil around ferrite rod is free. Glued the coil helps to avoid frequency drift when transmitter is moving.

This 3 transistors AM modulator is splendid for the price. I only regret that there is not a fourth transistor on the board to amplify the sound. IMA the potentiometer on the board to decrease the volume is useless because modulation index is pretty low even with maximum volume on the player.