The modulation meter works and the 866's change with voice changes, but there is no audio on the carrier.
Does the modulation meter show standby modulation current and does it show an upswing on voice? What does your scope show on the rf output connector into a dummy load? Are you monitoring yourself into a dummy load with a receiver nearby?
Have you safely measured the HVB+ on the caps of the 6146 modulator tubes? Have you tested the 6146 modulator tubes?
The grid control knob is very warm and while it can be set to 8 mils in zero position, it drops to 4 in transmit and can't be adjusted. I plan to replace the pot, but wonder if it is responsible for the audio problem? Thanks for any suggestions. Don, K5WSY
The Grid drive pot is underrated and will always get hot but does fail. RF drive has little to do with modulation.
Phil