Merv's Brain Dump

These are notes and thoughts generated by me and Claude AI.

The Antennas, Antenna Gear, Calibration and Tools are theory only and haven't been tested unless noted. OpenScad and KiCAD files may need to be reworked.

Rothammel's Antenna Book is great for theory and I'd suggest you get one. I need something more practical so, being an old fleet sailor, I got Claude to write up each antenna, antenna gear, calibration technique and tool in a Navy Technical manual style. Turns out, that makes a perfect link between Rothammel's and an antenna you build. Antenna gear, calibration techniques and tools give you a "how to" also.

I use Cheap Yellow Displays (CYD) for interface. It's an ESP32 with an LCD screen. AliExpress — get the touch screen one. $15–$20 USD.

Do you want to understand and maybe build a directional coupler? Look at MANUAL_RF_COUPLERS.md in Antenna Gear. Navy tech manual style brings it down to earth. You can build one if you like. CYD programming info is included.

Want to know how to build a GPS disciplined oscillator that keeps time with cesium-based clock accuracy? (~$20 USD). With this you can recalibrate your TinySA 30 MHz calibration clock. It was done at the factory, sure, but between that factory in China and your QTH, how many warehouses has it been in? And how many forklifts have played soccer with it on the way? So is it still in calibration?

The calibration may not matter if you're testing your own gear, but if you're comparing results with someone else, it does. If you're both calibrated to the same or similar standard (cesium-based clock) you'll have a meaningful conversation. If not you may be in the ballpark, but one team didn't show up.

The calibration ideas section shows quite a few more ways of getting cesium-based clock accuracy. I just picked my favorite. And it runs off a CYD.

How about a VFO? vfo_siggen/MANUAL_VFO_SIGGEN.md gives you a VFO with theory and how to build. When you build one, it teaches.

The Ham Radio Flash Card Quiz is my resource for studying for my amateur radio licenses. Right now the old Technician pool is used — when we go to the next one I'll update. It's the digital form of a flashcard machine I saw and used in the Navy. When you get an answer right it flashes green and you hear a pleasant tinkle. When wrong it flashes red and buzzes at you. Imagine a bunch of 18–20 year old sailors, one at the machine and the others shouting encouragement and right answers — and wrong answers. Speed run, go until you get one wrong. Most fun with a gang "encouraging" you. Best negative reinforcement training I've seen.

The Morse Code Practice — I took aphorisms from around the Internet, ran them through the ebook2cw software, and this is the result. Broken into message length and sent at various speeds. Files are named with their WPM and Farnsworth spacing. Have fun and enjoy!!

73   Merv   KO6NNH