This vacuum tube tester is built around an ATMEGA16 MCU with PWM controlled voltage converters for heater, grid and plate voltages, and ADC mode on inputs for measuring the voltages and currents. The original design and PCB come from a Polish magazine named Elektronika Praktyczna (Practical Electronics), designed by Adam Tatuś and Tomasz Gumny. I developed it into what you see here, a briefcase unit (inspired by vintage tube testers) with various kinds of tube sockets and a pin matrix selector for assigning functions to socket pins. Future developments include porting the code to ATMEGA32, allowing for a larger size of the built-in tube catalog, as well as developing computer-controlled interactive testing mode where the tester sets parameters based on the data it receives on the USB UART.
Oh, this? Not the way I do it now, with the superb Ariadna Tytan 1000 polyester threads in my favorite purple. The old thread liked to rip unexpectedly if I pulled it too hard - the new one is indestructible and I could probably hang myself on it and it'd do the job just fine. Got enough of it to last me a lifetime. Standard on all Keritech amps and devices since 2021.
Beautiful lacing on those wire harnesses!