https://stream.echo6.co/videos/watch/9776c809-9aff-4827-8853-a82f7d6b4475 Testing a one transistor CW transmitter based on the desription by SV3ORA here with some variations http://www.qrp.gr/emtx Use the biggest crystal you have or several smaller crystals in parallel (there's a risk of damaging crystals if you're not careful as currents are high). I used a BD139 transistor but you can use whatever you have if it operates on HF. NOTE: my circuit had some decoupling from the supply rail (10nF and 10 uF). Also have 0.1uF across the key contacts. Contents 0:00 Introduction 0:28 Circuit description 2:00 Testing 2:22 Coils 3:08 Current usage 3:58 RF output 5:17 How far does it transmit? 6:09 A bigger crystal 6:47 Another SDR test 8:29 Summary 9:04 Minimum QRP book 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) Mon, 13 Apr 2026 13:23:48 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/9776c809-9aff-4827-8853-a82f7d6b4475 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.