[NostalgiaRadioTime]

Excellent work! I've chased many tubes trying to find which one was the one causing just the symptom you described...that sudden "pop" on instead of a gradual volume increase as the set comes to life. It's frustrating when tubes test good, but yet one of the internal elements have a "hidden" fault that isn't known until the set is tried out. I've got a tube in my big round gold dial Silvertone that leaves that soft "whooshing" sound in the background noticeable when the volume is turned down. Still haven't found which one is the culprit on that.