05-22-2013, 07:55 AM
Hmmm.... That's pretty strange. Did you center-adjust the line test after placing the 5U4 in the socket? The 5U4 draws 3A of current.
Output tubes should be 6B4G, am unfamiliar with the 6A5.
Output tubes should be 6B4G, am unfamiliar with the 6A5.