A dirty transmitter: how far can its harmonic be heard?

About a 1 transistor frequency agile 200mW CW transmitter for 3.5 MHz. With circuit so you can build. Discusses the importance of low pass filtering with a demonstration of how far a harmonic can be heard. Also discusses efficiency and its calculation. Contents 0:00 Introduction 0:07 Circuit and description 2:15 Low pass filter 2:34 Keying issues 3:49 Measuring tx power 4:51 Origins of circuit 6:30 Demonstrating importance of the low pass filter 6:53 How far away can the harmonic be heard? SDR tests 12:40 How efficient is this transmitter? 15:36 Circuit (clearer view) 15:57 Minimum QRP book LPF info:    • A switchable QRP low pass filter for 3.5 a...   Reggie info: https://web.archive.org/web/201011240... 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)