Lou, on the 2nd pix, it looks like BOTH tubes are going red.? My guess is.... it's a grid to cathode short on one or both tubes.?
The baffling part is..... his grid and plate current meters are still reading zero.?
More baffling is..... it takes 5 mins for the problem to manifest itself.?
Typ with a grid to cathode short on just one tube.....? BOTH tubes will go red asap, as soon as you turn on the amp.
?
On a related note, on Eimac 3-500Z's, they typ hi-pot test 5 kv? from grid to cathode ( good tube).? ?On all the chinese ( good tube)? 3-500Z's.... they all only hi-pot test 1 kv from grid to cathode.?
