I acquired an older Yaesu FTM-400DR which I repaired myself after much regret in trusting the Yaesu butchers. All I needed was a relay, a capacitor, and a Mitsubishi RD70HUF2-501 from RF Parts.

Since the GPS on these units were known to be hot steamy garbage, I purchased a discounted GPS5 from Byonics and made my own harness to connect power from a 12V socket and a 2.5mm to connect to the head unit of the radio. When set from external GPS source then the APRS on this unit worked. However, there was one issue… when scrolling through the different displays, if you got to the one that shows the satellites the radio could see the whole unit would lock up very rapidly.

I used it quite a bit and during late July 2022 skywarn event I needed to reboot the unit as I triggered the bug that made this radio crash, but sadly I connected the positive PowerPole to the negative and I believe there was grounding through the antenna.

May it rest in pieces. It was donated to a fellow ham for parts.