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The U-6V6

ceylon said:
this is excellent work. im gobsmacked by how tidy and compact it is. im eager to rereD thru the entire
build thread in one sitting.
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Well, it's at the end where there is the most important points ! ;)

Thank you @gadget73 for your observation about the 6K8 screen resistor. I wanted to balance the plate voltage, and it was not a good idea : reducing the value to 470R allowed to save a bit more power output in Pentode mode (2.6W instead of 2W) without any issue with the 6V6GT. Well, I must confess that the 1st NOS 6V6GT was in overcurrent right out of the box (with 60mA instead of 45mA plate current in bogey tube datasheet conditions), so it also got me wrong ! :rolleyes:

Thank you Guys who encouraged me to add the Triode/Pentode mode, while I was skeptical to use it... :thumbsup:

T
 
maybe gassy tube? Happens, just because its old doesn't mean its any good. I wonder if some of these NOS tubes we find now were rejects from decades ago.

glad its working out.
 
gadget73 said:
maybe gassy tube? Happens, just because its old doesn't mean its any good. I wonder if some of these NOS tubes we find now were rejects from decades ago.

glad its working out.
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Yes indeed - thanks ! A gassy tube : that's probably the case. I'll gas-test it with my Hickoks 539C and 600 to see how it behaves...

T
 
they don't tend to have much visible glow unfortunately. Maybe some pink or purple down inside the plate structure. Mercury vapor or cold cathode rectifiers and gas regulators make better visual display pieces. Gas regs come in a range of colors depending on voltage too.
 
gadget73 said:
they don't tend to have much visible glow unfortunately. Maybe some pink or purple down inside the plate structure. Mercury vapor or cold cathode rectifiers and gas regulators make better visual display pieces. Gas regs come in a range of colors depending on voltage too.
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I don't light them up, just hang them on the tree.
 
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