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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

More assorted ramblings on the Aux Band ROM:

The device is listed as a TBP18SA030. Equivalent to an NS82123 and similar. These can be found on the auction site and via a few other sources...but the programmers may be a little harder to source.

When I was researching this project a while ago I ran across the following:



I bought a couple of them plus a programmer that supports the SST39SF010. If one leaves the Aux Rom socket empty, all the data lines should be set "High". Thus, to set a band segment one will have to program a "0" into the bit location. Per earlier comments, 5 bits should cover the entirety of the HF spectrum...leaving 3 bits for housekeeping stuff. I revisited the CPU Board this morning before typing out this reply and there doesn't appear to be anything special going on with the high (or low) bits of the band-data byte: All 8 are put on the bus and processed. Thus, any filter or VCO switching logic is probably done as a function of the CPU programming.

Those extra bits could be used to set the VFO (Ham or Gen) and for TX Inhibit. A bit of empiricism is going to come into play, one supposes. Given I can program the Flash ROM as many times as needed, I'm thinking of setting Bit 1 high, 2-5 low and 6 and 7 low...as a baseline. Then test and record. All 255 combinations could be tested sequentially and I just may do that to flesh out a data sheet completely.

There is still the matter of filter switching on the RF Unit (D70-D72) but I think I figured out what Yaesu did with regards to the control logic here. First things first: Getting the band segments recognized and the rig generating the correct LO/control signals.

73 - Fred, N8YX

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