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…
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…
“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…
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…
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.…
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…
Hollow-State Design
Grayson Evans, KJ7UM, Copyright 2016, 2020 If you are interested in building electronics, I think you will be interested in “Hollow-State Design (mostly for the Radio Amateur) 2nd Edition” I wrote this book to help radio amateurs and related electronics enthusiasts to discover (or rediscover) the fun of building electronic circuits with thermatrons (vacuum tubes).…
Home Network DVD Course Workbook
By Grayson Evans, Copyright 2016 One of the most successful and well-watched DVD courses produced by Training Reels was the Residential Networks course. This was a 3.5 hr DVD course that covered the design and installation of every sort of “network” in homes and/or light commercial. “Home Network” is a broadly used term that means…
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