Yes, they do, Art. I believe the warm-up timer on the Alpha 78 is set for around 2 minutes. 73 de Mike, W4EF.............. From: "Arthur Moe" <kb7ww at easystreet.com> > Those of you who are running amplifiers with these tubes I have a question. > > Do the 8874's require warm-up time, if so how much ?? > > Art > KB7WW