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Old 3rd April 2012, 01:01 AM   #31
MelB is offline MelB  Canada
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My that's some coincidence. I just built a GM-70 amp. Insanely nice tube. And very cheap. That's a hammond 18v 5 amp trans for it's filament supply. Ya 60 watts for the filament. It's just like a light bulb. This is my first iteration. Just using a Hammond 300-0-300 transformer gives me 810v on the plate. The power supply is designed for max 1200v though. I will switch in a 400-0-400v Hammond after some more testing. Should get about 1050v on the plate. I'm stopping there.
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Old 3rd April 2012, 01:11 AM   #32
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Originally Posted by MelB View Post
My that's some coincidence. I just built a GM-70 amp. Insanely nice tube. And very cheap. That's a hammond 18v 5 amp trans for it's filament supply. Ya 60 watts for the filament. It's just like a light bulb. This is my first iteration. Just using a Hammond 300-0-300 transformer gives me 810v on the plate. The power supply is designed for max 1200v though. I will switch in a 400-0-400v Hammond after some more testing. Should get about 1050v on the plate. I'm stopping there.
I would put a mirror between tube and transformer. Too hot and too close.
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Old 3rd April 2012, 02:04 AM   #33
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I would put a mirror between tube and transformer. Too hot and too close.
No no no! That will just reflect the heat back to the tube's plate! The endbell won't be hurt by a little heat.
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Old 3rd April 2012, 02:17 AM   #34
MelB is offline MelB  Canada
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It's a lot further away than it looks in the other picture. It is not a problem at all.
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Old 3rd April 2012, 02:18 AM   #35
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No no no! That will just reflect the heat back to the tube's plate! The endbell won't be hurt by a little heat.
It depends on how much is "Little". And how "cheap" is transformer for such an amp.
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Old 3rd April 2012, 02:19 AM   #36
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It's a lot further away than it looks in the other picture. It is not a problem at all.
Sure, I see now how far it is, how anode is oriented, and how shiny is the bell itself.
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