Admiral Imperial 330 Chassis 16ASIC

[bgadow]

I would make sure there weren't some misrouted wires; perhaps the speaker wire or maybe the line from the tuner is picking up intereference? If it is a parallel chassis I think I would just start pulling some select tubes one by one and see if any will make the noise go away; not so easy with a series string. Have you cleaned the tuner? Just some ideas.