New interesting item on the bench

Discussion in 'The Workbench' started by chuckharmonjr, Jun 10, 2019.

  1. Goldguitarguy

    Goldguitarguy Active Member

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    My wall voltage at the switch is 123vac so that would be where in lies the numbers difference then.

    Sorry OP for the hijack
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    60 ma for one tube or both tubes?
    I think about 37 ma per tube at least...

    What you are reading is plate + screen current not plate current alone.
     
  3. Goldguitarguy

    Goldguitarguy Active Member

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    I measured the voltage from pin 3 to ground. Is that both the plate and screen voltages? So I would subtract the screen voltage from that number or how does that work? And yes I believe it is for both tubes, I just googled how to bias a hot rod Deville and watched a tube Depot video on YouTube. I'm still learning the the basic techie stuff.
     
  4. ampmadscientist

    ampmadscientist Well-Known Member

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    The voltage on pin 3 of the output tube is the plate voltage.
    The voltage on pin 4 is the screen voltage.
     
  5. mickeydg5

    mickeydg5 Well-Known Member

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    60mV/mA is for both tubes, 6L6GC, at the 1 ohm cathode resistor as per the schematic you are referring.

    The 499VDC is due to 120-123VAC from the wall versus 117VAC.
     
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  6. Goldguitarguy

    Goldguitarguy Active Member

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    Definitely wasn't something on my radar as a factor ever...Thanks for the lesson Mickey
     
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  7. mickeydg5

    mickeydg5 Well-Known Member

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    You are welcome. :yesway::)

    Chuck, what is going on? :hmm:
     
  8. chuckharmonjr

    chuckharmonjr Well-Known Member

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    I have parts on order to rebuild the bias supply circuit. Also had a few traces that looked suspect.
     

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