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previous: Bruce For what it's worth, I blew up my f... -- 4/12/2000 4:43 AM

Re: Plate voltage on BFD/HI-Volt 6V6EH

4/12/2000 5:01 PM
John Stokes	Re: Plate voltage on BFD/HI-Volt 6V6EH Wow, Bruce. That kind of flies in the face of the testing LV has done. Were you running the stock 470 screen resistor or did you replace it with the 1k? I put a set of the EH in a friend's BFD (no R), and it runs the plates at about 425 or so. I changed the screen resistor to 1k, and biased about 27 ma or so. They're still hanging in there. No red spots on the plates, but I do see a little glow internally on signal peaks, I take that to be the screens starting to glow. Hasn't the weak point in those Sovtek 6V6s always been the screen grid? They overheat, melt and then short. Maybe going to 2.2k on the screens would help that, at the expense of a watt or two of output power. On the tube that shorted, what elements shorted? Was it the screen to the beam former or to the control grid?

4/12/2000 5:01 PM

John Stokes

Re: Plate voltage on BFD/HI-Volt 6V6EH

Wow, Bruce. That kind of flies in the face of the testing LV has done. Were you running the stock 470 screen resistor or did you replace it with the 1k? I put a set of the EH in a friend's BFD (no R), and it runs the plates at about 425 or so. I changed the screen resistor to 1k, and biased about 27 ma or so. They're still hanging in there. No red spots on the plates, but I do see a little glow internally on signal peaks, I take that to be the screens starting to glow.

Hasn't the weak point in those Sovtek 6V6s always been the screen grid? They overheat, melt and then short. Maybe going to 2.2k on the screens would help that, at the expense of a watt or two of output power.

On the tube that shorted, what elements shorted? Was it the screen to the beam former or to the control grid?