nanoVNA balun test harness by N9LR

Block diagram and schematics (not for simulation or PCB) of a hand wired test board to automate balun testing using nanoVNA. Only intended for HF range, not tested on UHF/VHF, but chances are it will work OK there as well.

Board supports:

• SOL Calibration 
• S11 using 50 ohm
• S21 in DM (differential mode)
• S21 in CM (common mode)

Current implemnetation uses dual relays (had those in stock), but can be simplified with SPST

NOTE: asumtion is that nanoVNA internaly bonded grounds have no significant impact on test

Board pictures here https://photos.app.goo.gl/ceLchzVR9721NXH3A