Following Colin's M1BUU example, I built a my MTR battery - LIPO 3S jumper cable with a 1A fuse and 1N4001 diode. Voltage at the terminal with a fully charged battery is 12V. The diode was installed within the 1.7mm DC connector - using some shrink tube to isolate it from the negative terminal.
I calibrated the MTR to output 5W as recommended with 12V.
TX current is 630mA
RX current is 35mA
All ready to go for the next activation with the new power pack.