SA2CLC radio stuff

Handling negative voltages and getting boards sponsored by PCBWay PCBWay supplied the PCBs for this project as part of a collaboration — my write-up here is focused on the technical aspects of the design and build. The problem  In the amplifier project, I need to measure currents and voltages. Plate voltage (Ua), plate current (Ia), screen voltage (Ug2), screen current (Ig2), control grid current (Ig1) and also control grid voltage (Ug1). My first approach failed due to me not thinking properly. The current measuring relies on shunt resistors, which is a proven and reliable way to measure dc current. A resistor is placed in a branch of the power supply and by measuring the voltage drop across the resistor we can calculate the current, using ohms law, I=U/R.  Upon testing the amplifier I realised that the arduino would not measure any current. Voltage measurment (Ua, Ug2) uses voltage dividers, and that worked as planned.  Eventually it dawned upon me that I was trying to ...

Elecraft K3 – Rear mic jack not working I recently decided to upgrade the headset in my “modern” station. Although my Heil Pro headset has been working fine, it becomes uncomfortable during longer operating sessions. At Mike (SJ2W), Bose QC25 headphones combined with Antlion ModMics have been used for many years. After working a few contests there, I can confidently say they are much more comfortable than the Heil headset, and way cheaper, since these headphones and mics are widely used by gamers. I picked up a used Antlion ModMic and a pair of Bose QC25s, and with that I wanted to clean up the wiring a bit—specifically getting rid of the bulky Heil “K” adapter with its large 1/4″ ptt jack on the front panel.  Since I only use a footswitch for ptt I felt it was annoying to have it cluttering the desk. My plan was to use the rear connectors for audio on the Elecraft K3, since there are plenty of them. Line in, Line out, phones, mic, and speaker output.  Unfortunat...