Radio tinkering notes

This section of my capsule is, as of around August 2025, under undergoing sporadic construction. I'm going to start putting stuff up intermittently, even if it's not necessarily complete or polished, rather than waiting until I have enough time to do a perfectly clean job of things one-by-one (because that'll probably never happen). I will revise and reorganise and update as I go along. The "dedicated reader" experience is therefore likely to be a bit inconvenient and chaotic, compared to, e.g. subscribing to my gemlog. That's okay, because I don't expect there to be many dedicated readers of this section anyway, at least not while it's being managed this way!

Introduction and scene setting

Technical stuff

• Using varactors for tuned circuits
• Using CMOS switches as mixers
• Everything you ever wanted to know about SITOR encoding

Some of my projects

• TA-7642 receiers
• NE602 NAVTEX receiver
• "The CMOS miracle"

Amateur radio stuff

• An incomplete history of the NE602+LM386 direct conversion architecture