Dave,
Best way to get extra coverage (IMHO) is for the group at large to reverse-engineer the Aux Band PROM programming, or to possibly get ahold of a JA-issue Technical Supplement (which - if like the FT-301 stuff - has service and mod information which never made its way into NA-distributed materials).
8 bits of data at each address; the chip connections allow for selection of 3 discrete addresses. Assume 6 of the data bits will be used to set the band edges (60 possible combinations) and that possibly leaves two for other (TBD) housekeeping functions. I have to study the interconnections again but I think all VCO and filter select data is controlled via that band segment data, rather than as a discrete nibble. Some RF Unit changes have to be made to enable the new "Amateur" Band Pass filters and the components themselves will have to be sourced. I've gotten very good at building these things...
Thoughts are to fit 5.0-5.5MHz (for 60M) and then work out the programming and coil data for 20-20.5, 26.0-26.5, 26.5-27.0, 27.0-27.5 and 27.5-28.0. That would hit all the popular transverter ranges. Proper selection of BPF and LPF is really the only way to go here and I don't see Yaesu's Gen TX mod offering anything in that regard unless the radio is operated above 22MHz. Even then I'd like to see a correctly tuned front-end circuit in play.
73 - Fred, N8YX
