Trying to build the web-interface for the AMSAT-DL up and down converter (AMSAT-DL Journal 3-2020). I need to find the contact (pin) to route the TX data of the downconverter to the RX port of the upconverter to have both serial data available for the web interface. According to the article, the revision 4.3 of the upconverter is supposed to have a separate pin for RX (it has one for TX). However, it looks like there is none, unless someone can point to it. It is not available at the 6pin connector where the TX pin is located. The only option appears to be connecting it directly to pin 15 of the PIC (18F2520) or the tiny resistor in front of it. Appreciate any thoughts.....
Thanks, Stefan VE4SW