SP_& uses Nano A7 as a digital output (verboten!) to control CO buffer

[prt459]

As per the description. On Arduino Nano A6 and A7 (unlike A0 to A5) cannot be used a digital output pins. See Warnings para here: https://www.arduino.cc/reference/en/language/functions/digital-io/digitalwrite/

Resolution: Chase down which projects attempt to use A7 for digital output (SP7 at a minimum) and note the problem. Also, explain why SP7 works on CW! Did I tie the CO buffer to +12V Tx?