https://stream.echo6.co/videos/watch/73176ae4-6ee1-479c-ae42-9be9c2a322dc The TL431 is a shunt voltage regulator IC intended to be used like a zener diode. But unlike a zener, which has an anode and cathode only, the TL431 has three wires (the extra being a reference). I previous found it was an effective high-gain audio amplifier, able to drive a speaker from a crystal set. In this video I use it as a modulator to allow a 7 MHz CW QRP transmitter to generate AM. As you'll hear the sound quality produced is excellent. PS: If you liked this video please consider supporting Amateur Radio VK3YE by: Subscribing on YouTube,, Checking my books page at https://books.vk3ye.com, Shopping on Amazon via: https://amzn.to/3iiDQXv, or, Shopping on eBay via: https://ebay.us/i9DuWP (then if you buy something I'll get a small commission at no cost to you) Sun, 26 Apr 2026 17:27:09 GMT https://validator.w3.org/feed/docs/rss2.html PeerTube - https://stream.echo6.co https://stream.echo6.co/client/assets/images/icons/icon-512x512.png https://stream.echo6.co/videos/watch/73176ae4-6ee1-479c-ae42-9be9c2a322dc All rights reserved, unless otherwise specified in the terms specified at https://stream.echo6.co/about and potential licenses granted by each content's rightholder.