RF Circuitry Links

Posted on Feb 4, 2014

The 7th overtone of 18mhz (17m) is 144mhz (2m) smack dab in the CW region. Icarus a HAB project run on advertising revenue that seems successful and has launched many balloons with some awesome photos. Robert Harrison knows his stuff! Lessons in Electric Circuits A very good (free) textbook. Anyone starting to learn about electronics should start by skimming

RF Circuitry Links
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over relevant chapters of this text! 1W CW transmitter kit Although I don`t own one, I appreciate the kit and love the schematic. This guy uses a buffer chip (a 74HC04n, similar to a 74HC240 often used in QRP too) to act as an oscillator and small amplifier. The output is then further amplified by a 2n3866 transistor. 30M Solar QRSS transmitter such an inspiring project! This guy uses a buffer chip (74hc245) to amplify the output of CKOUT of a microcontroller clocked at the transmit frequency. The thing is solar powered, and has a unique temperature compensation mechanism which uses the chip`s built-in thermosensor to adjust its offset. I haven`t seen this technique used anywhere else in a QRP transmitter! Everything this man does is impressive! His QRSS section is wonderful, and I won`t detract from it by trying to describe it here. He also has a simple QRSS receiver circuit based upon a SA602, something I replicated (tuned front-end not shown) to operate my W4DFU QRSS Grabber at the University of Florida. MOSFET Switched Mode  Amplifiers a wonderful document, read it multiple times! Transistors are traditionally used in many QRP circuits as amplifiers, but MOSFETs have some unique qualities which in many ways makes them easier to work with in simple circuits. I found this guide EXTREMELY helpful!

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