Crystal oscillator modules: how far will they transmit?

Range tests on a 28.571 MHz crystal oscillator module putting out a few milliwatts of power. The module was keyed with its output fed to a 1/4 wavelength antenna plus radial.

The module is fed with 5v via a 7805 voltage regulator. A microcontroller keys it. For anything other than a quick test the use of a low pass filter (100pF x 2 & 0.2uH) is recommended to attenuate harmonics.

This test was with Morse. Modules can be made to transmit AM if their supply voltage is modulated but their transmitting range will be less. DSB should also be possible if their output is fed to a balanced modulator.

Similar unit built by others http://www.ae5x.com/docs/Fire-Ball_QRP_Rig.pdf

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Видео Crystal oscillator modules: how far will they transmit? канала Amateur Radio VK3YE