An RF Engineer turned amateur radio enthusiast exploring radios, amplifiers, antennas, and clever circuits
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Introduction
Welcome, fellow Amateur Radio enthusiast! As an RF Engineer and new ham, I am excited to share my ideas, experiments, and mistakes I make along the way with you through this blog, as I have learned so much from the community in my first few months. Whether you are just starting out or have 50…
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New Antenna: Simple 20m horizontal half-wave dipole
I signed up at the local club to be an activator for lctota.org, so my 2 element beam pointed at New Zealand wasn’t really ideal. I really needed an antenna that would cover as much of the U.S. as possible, so I went with a simple horizontal dipole facing East / West. I have a…
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New Spring Project – a travelling companion for my IC-7300
I think work is going to be too busy for my grand project. But a fun, simple project for this spring: add a power supply output (13.8V 20A) to my 20 meter amp for my IC-7300, and package it up in an attractive, slim box. Maybe double the output power while I’m at it, just…
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New Project: My Summer Radio
I think I’ve settled on my next project. I’m getting sick of random polarization fading ruining a good conversation. So I think my next project will be a 10 meter radio set up to support circular polarization, battery powered with a fiber optic interface so there are no cables to mess with my antenna pattern.…
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What is a Class F amplifier and why does it matter?
The short answer is efficiency. A true linear amplifier is limited in its efficiency. A realistic number is 60%, meaning if your output is 300 watts, you’ve got 200 watts of heat to get rid of. A class F amplifier is NOT a linear amplifier. The transistor is driven with closer to a square wave…
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My Amplifier Works!
The tests yesterday went well enough that I was comfortable getting on the air. So far the GaN FET is holding strong! I think the tweaks to the circuits improved efficiency (around 90% PAE I think) and removed the risk of a 200 amp current surge as it turned off. The Class F portion of…
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Class H & F Amplifier Progress
The surface mount parts are on! I still need to do all the through hole parts, and then test the darn thing… more updates later today. Update 1: Through hole parts are on, mechanicals look good. Need to add heat pipes from the FETs still, but the fan is nice and quiet (which was the…