Cheap and Chirpy 1 transistor CW transmitter 

Testing a one transistor CW transmitter based on the desription by SV3ORA here with some variations 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
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