When I say 'final', I of course mean the final mod to be made directly to the radio! This will be the addition of the ribbon cable(s) required to connect the microcontroller to the synthesizer. Ive decided to go ahead with this now, even though the radio is not operating quite right,as it will give me a set of 'break-out' connections to the synthesizer, which will allow me to safely and conveniently meter out the data coming from the decade switches. Hopefully this will allow me to identify which switch lines are not functioning quite right, and work out if its a voltage drop issue or a physical contact problem.
This will make the list of mods done to this rig as follows -
1. All decade switches output pins have BAT85 schottky diodes to prevent data contention
2. SSB and CW(N) modes have 2kHz offset removed
3. CW(W) mode changed to provide select line for LSB
4. S-meter added
5. One audio accessory port replaced with external connection for data control
6. 2-3.1MHz range widened to 1.8MHz to cover 160m band
7. Synthesizer programming lines available for external control
A pair of ribbon cables have been found out for this task, which should be easier to route inside the radio casing than one big flat one. They have been marked with a red band for the first series of connections, and two red bands for the second series. The ribbon carrying the external data connections is marked with a pair of red crosses!