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Auxiliary band ROM


 

Reading through the various literature and commentary from yesteryear about the FT-980, it's mentioned that an Auxiliary band ROM was never offered for the rig - nor was any programming data provided...at least in the English version of the Technical Supplement.

The ROM is a bipolar type and a 74188/74288 appears to be a suitable replacement. There are others.

A gent by the name of Callan Brown offers something termed a "FLEP" - a daughterboard which allows the use of a QFP type EEPROM in place of a bipolar ROM. It was originally designed for the video game market. I bought a couple last year and when I source a couple of Harwin headers I'm going to have a go at developing a programming map for the ROM. 60M coverage will be high on the priority list...and since there are only FF combinations of data to try it shouldn't be that difficult to map all the HF ranges. Even if I have to try every value.

Before I start this effort: Is there anyone in the group with a '980 which actually had an Aux band ROM installed....either by Yaesu or by a 3rd party? I have four of the rigs at present plus a spare CPU Unit and none have the ROM present. Nor have a number of other 980s which I've examined. Alternatively, do we have access to the Japanese-language Technical Supplement (which may contain the ROM programming data)?

73 - Fred, N8YX


 

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HI
I HAVE 2 980S WITH THE YAESU SUPPLIED rf gen boards. they were supplied right after i bought each radio
but i am not technical to understand if thats what you mean.
bob donchez
wb3hyb


On Jun 9, 2020, at 11:25 AM, Fred_N8YX <N8YX@...> wrote:

Reading through the various literature and commentary from yesteryear about the FT-980, it's mentioned that an Auxiliary band ROM was never offered for the rig - nor was any programming data provided...at least in the English version of the Technical Supplement.

The ROM is a bipolar type and a 74188/74288 appears to be a suitable replacement. There are others.

A gent by the name of Callan Brown offers something termed a "FLEP" - a daughterboard which allows the use of a QFP type EEPROM in place of a bipolar ROM. It was originally designed for the video game market. I bought a couple last year and when I source a couple of Harwin headers I'm going to have a go at developing a programming map for the ROM. 60M coverage will be high on the priority list...and since there are only FF combinations of data to try it shouldn't be that difficult to map all the HF ranges. Even if I have to try every value.

Before I start this effort: Is there anyone in the group with a '980 which actually had an Aux band ROM installed....either by Yaesu or by a 3rd party? I have four of the rigs at present plus a spare CPU Unit and none have the ROM present. Nor have a number of other 980s which I've examined. Alternatively, do we have access to the Japanese-language Technical Supplement (which may contain the ROM programming data)?

73 - Fred, N8YX


 

Robert,

The module you describe is the same type I have here - three of them in total. It's essentially a high-pass filter which goes into the Aux Band filter spots on the RF Unit. This board along with a few diodes allows the Gen VFO to transmit and uses the highest-frequency low-pass filter chain in the rig to reduce spurious emissions.

It's a kludge at best. Might work for the transverter/CB crowd that wants output from 24-30MHz but on 60M I'd be leery of the 3rd and 5th-order harmonics.

The PROM I mentioned goes on the CPU Unit in a socket. You also need to install diodes on the RF Unit along with discrete filter components (i.e., capacitors and tunable inductors) and you end up with 3 extra 500KHz segments. These segments are documented in the FT-980 CAT reference, so provision for addressing them via the CPU is present in the firmware.

73 - Fred, N8YX