Funny you should mention FEC, I used to make trips to the yard here in Jax to fix the mobile phone on the President's car. Typically the mechanics would fool around with the wiring in the battery box and tie the phone onto the 60v buss. Since it ran on 12v it didn't care for this much.
Any of you guys heard of Control Chief? I used to work on one of these at the Oxy chemical plant here. It was a remote control for a locomotive, Oxy used it in a 1949 GE loco that moved the cars under the feed hoppers at the plant. This thing was a major PIA to work on, especially if I had to work on the antennas which were mounted over the engine. Nothing like crawling over a huge desiel engine with 40 years of
oil and soot built up.
I did get to drive the train a couple times which was fun.