DR-135 TNC 5V regulator modification

I recently acquired an Alinco DR-135 radio with an integrated EJ-41U TNC unit. I decided to replace the TNC with an Argent Data Tracker3 T3-135 module. After installing the module, however, the TNC board would not power up. I measured the 5V line feeding the TNC module at around 3.5V. When I replaced the module […]