A frequency agile 2 transistor 7 MHz FM exciter

4,982 views · Published 11 August 2018 · 3:52 · Indexed 23 September 2026

Channel: Amateur Radio VK3YE · 2018 · Science & Technology

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Very few people use HF FM even though it's easy to generate. It's not a QRP mode as it's less efficient than SSB or DSB.  But if signals are strong the audio quality can be excellent.  This video describes a frequency agile 2 transistor exciter using a 7.2 MHz ceramic resonator. See my previous video (Frequency modulating a crystal oscillator for 147 MHz FM) for more information on the circuit. 

It could be used as the basis of a transmitter for 7 MHz FM experiments (best during the day as there's less interference).  You may even be able to link it to a VHF or UHF FM rig to make a crossband repeater.

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