Discussion in 'Amplitude Modulation' started by KA4KOE, Jun 7, 2017.
Mikee fixed his parasitic problem. Nice clean carrier now. He's happy as a pig in slop.
Another electronic Lazarus!
Yup! I'll have to remember in the future to check ALL large tapped power resistors underneath the tap! It was conducting just enough to lead me to believe it was fine. Once I moved it out of the normal range, I saw that a lot of the windings were toast. Only the tap itself was keeping it going - and not well either. It was the one used to set the grid bias on the 807 RF driver tubes. Why the grid voltages and waveform looked fine on the scope, I don't understand. But after replacing that power resistor with a few regular high wattage resistors (as a voltage divider) to fix the bias where I wanted it, the problem was gone!