I'm experiencing the well-documented TX power overshoot issue with my IC-7300 when using it with my Heathkit SB-1000 amplifier. The 7300 produces RF to the amplifier after PTT drop when going from transmit to receive, causing large RF sparks on the relay and potential damage to the amp itself. Has anyone found a solid workaround for this besides avoiding amplifiers entirely? I've read about bandpass filters helping but looking for specific recommendations on interface solutions or timing adjustments that actually work in the field.

The IC-7300 suffers from overload problems in the face of nearby strong signals like you might find at Field Day, and proper bandpass filters are the solution. For your amp issue, try adding a sequencer with adjustable timing delays between the radio and amplifier PTT lines.

The FT-991A does not have that overshoot problem - my Heathkit SB-1000 is perfectly happy with it, and the 991A just sounded better with better SSB modulation. You might consider upgrading if the problem persists.

I solved this exact issue by installing an MFJ-1708SDR interface between my 7300 and Alpha amp. The built-in QSK timing controls eliminate the overshoot completely. Worth every penny for reliable amplifier operation.