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How to design thermatron power amplifiers
Hollow-State Design, 3rd Edition
Hollow-State Design, 3rd Edition is available from: Lulu Press: tinyurl.com/hollowstatedesign3 eBay: search for "hollow-state design" Electric Radio bookstore: ermag.com/product-category/books/ Listen to the "Deep Dive" Podcast review of the first two chapters:https://notebooklm.google.com/notebook/729c12a2-bd2d-4270-ab84-b508e0f443ac/audio This is the 3rd Edition of the classic Hollow-State Design book by Grayson Evans, an authority on thermatrons (vacuum tubes), their use primarily in… Continue reading Hollow-State Design, 3rd Edition
Hollow-State Homebrewing Video and Podcast
A new video on how to design and build a simple one-thermatron homebrew transmitter was posted to YouTube. I think you'll like it. Click above screenshot to view the video, or click: https://youtu.be/_kFIOBj4NLE This is a brief review of the video by the "Deep Dive" Podcast:This YouTube video by Grayson Evans, known as "KJ7 Uncle… Continue reading Hollow-State Homebrewing Video and Podcast
A 51S-1 Restoration Story
I came across my Collins 51S-1 in a big junkyard in Ankara, Turkey around 2012. It was in a pile with a lot of other electronic scrap, probably from one of the decommissioned NATO listening stations outside Ankara. Don’t remember what I paid the guy for it but it was cheap. It didn’t have a… Continue reading A 51S-1 Restoration Story
Experiments with Varactor VFO Tuning
(Took me a long time to post this, sorry. I wrote it in 2023 summer I think. Posted today Feb 17, 2024) I’ve been experimenting with several homebrew thermatron VFO designs lately. Typically, my VFO design is for a single band, single conversion receiver to mix with the incoming RF and cover 250 to 350… Continue reading Experiments with Varactor VFO Tuning
“Valve” vs “Tube” vs “Thermatron”
One of the compelling reasons, in my opinion, that transistors hastened the replacement of tubes in the late 50’s and early 60’s was due to the name “transistor”; one of the many things transistors had going for them. “Transistor” sounds way cooler than “valve” or “tube”, and if you look it up on Google, there… Continue reading “Valve” vs “Tube” vs “Thermatron”
The 6BN6, An Amazing Little Mixer
By Grayson Evans, KJ7UM, Copyright 2020 INTRODUCTION The 6BN6 Gated Beam thermatron is unique. It’s constructed like no other thermatron I have ever come across in radio electronics. It was the only tube of its type ever built1 but fortunately it is still readily available at low cost. For some time I have wanted to… Continue reading The 6BN6, An Amazing Little Mixer
Mixology
By Grayson Evans, Copyright 2020 In a previous article1, I discussed the history and technology of beam-deflection mixers. As part of the research designing and building mixers and their test circuits, I ran into an old and familiar problem: understanding how mixers actually work and why one mixer is better than another in different circuits.… Continue reading Mixology
Hollow-State Homebrewing, the MOVIE
Grayson Evans, KJ7UM, Copyright 2020 This is the movie version of the famous Home-State Homebrewing course. It was presented at the 2020 QSOToday Virtual Ham Convention. It is about 18 minutes. Enjoy.
The Future of Architectural Lighting
Grayson Evans, Copyright 2020 This video (click on photo) was created as an AIA credit course for Architects. It demonstrates and explains the future of architectural lighting technology, lighting automation, networking, and its effects on human health and well being. It covers the nearly complete transition to LED architectural lighting including how LEDs works, color… Continue reading The Future of Architectural Lighting
Grayson Evans's Technical Documents 