Dave,
Not sure - going on some data from the FT-301 group. Randy, W7CPA managed to get ahold of the JA-release documentation for an FP-301D (w/ ID timer) and within was the layout for programming the PROM with your call sign.
Stands to reason that the FT-980 Aux Band PROM info may also be in limbo somewhere. If Chip knows of documentation and can release it for use, I'll be glad to work through the RF Unit end of things - including winding the various BPF coils. 60M is definitely on my Want list. When all is said and done with programming and RF setup I'm going to throw the converted '980 on my spectrum analyzer and verify it meets emission purity requirements.
On the old list (circa 2010) someone claimed to be in the process of reverse-engineering and re-writing the main PROM for the CPU. I've played around with 8085 programming and may very well attempt to do same, but the Aux Band Challenge needs completed first (too many projects in the queue...).
73 - Fred, N8YX
