[FLY135]

I'm working on my first project, which is a reverb amp that I'm trying
to turn into a guitar amp. I'm confused about the rectifier circuit.
It's a 5Y3 tube. The heater goes to pins 2 & 8. Pin 8 is tapped to a
large electrolytic cap. The question is... Is the heater and the
cathode the same, or at least next to each other? If so wouldn't the
tap to the cap be negative? Shouldn't the cathode be negative?