Installed a jumper on the circuit board to allow the ELT to match up to the 4800 baud rate of the GPS antenna. I used the wingtip APRS Byonics GPS antenna to feed info to the ELT. Ran 12 V power from VPX and soldered the mini DIN connections at the ELT. Powered on, ran test during the 1st 5 minutes of the hour testing period and everything worked.
Added jumper to lower baud rate to 4800, matching the GPS feed.