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Vacuum Tube "grids"

Discussion in 'Electronic Design' started by Jon Slaughter, Oct 22, 2008.

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  1. Phil Allison

    Phil Allison Guest

    "Tim Shoppa"

    It is not too uncommon to use tetrodes or pentodes in "triode mode" by
    tying the grid and screen together.


    ** That is completely false and will not work.

    In "triode mode" the screen grid is tied to the plate while the suppressor
    grid or beam plates are tied to the cathode as usual. The screen grid is
    crucial to the operation of a power tube - if tied to the cathode the tube
    will barely pass current, if tied to the plate you have a triode. If the
    screen supply voltage is insufficient, the tube will not pass full current
    and lack gain.

    If the screen supply voltage is set too high, it will become the final
    destination for far too many electrons and quickly burn out from
    overheating.


    That doesn't mean the screen grid
    is the same as the control grid, in fact in beam power tubes the
    screen grid is sometimes better identified as a "beam forming plate".


    ** Nonsense - see any tube data book for how beam plates are connected
    internally to the cathodes of beam tubes, eg;

    http://www.pentodepress.com/tubes/6L6.pdf




    ....... Phil
     
  2. Eeyore

    Eeyore Guest

    I won't disagree with that but Jamie says some amazingly cretinous things too.

    Graham
     
  3. Eeyore

    Eeyore Guest

    He never acts in remotely any civil way to me. Clearly he's fearful of people
    with greater experience and intellect and compensates with hostile responses.

    Graham
     
  4. To call such a project "audio" is like calling astrology "astronomy".
    You have a great opportunity to learn something here and, instead, you
    appear to think you are doing something worthwhile by wallowing in
    semi-ignorance.

    For goodness sake start to tackle this project in an adult way and learn
    something about it before you waste hours or even years of your life
    pissing about with something which has already been well-researched.

    If you carry on without knowing what you are doing, your project will be
    treated with the contempt it deserves. ...but with a bit of serious
    background reading and your interest in the 'artistic' side of audio,
    you could gain a good understanding of valve distortion effects which
    would serve you well in future.
     
  5. Eeyore

    Eeyore Guest

    Starting by understanding the function of the control, screen and suppressor
    grids would be a good start.

    Graham
     
  6. Eeyore

    Eeyore Guest

    That style of design always fascinated me. It's quite clever despite the defects
    you mention.

    Graham
     
  7. Guest

    This is Jon Slaughter you're talking about. Tomorrow he'll be asking
    about something completely different and ignore you there as well.
    Plus he'll never learn the difference between your and you're, and
    he'll always be an apostrophe pluralizer...
     
  8. Eeyore

    Eeyore Guest

    Sadly this is likely all too true. In the UK we often call it the
    'greengrocer's apostrophe' btw. As in Apple's, Pear's, Tomatos's etc.

    In pubs I've even seen chalked up on the menu board, Fish and Chip's.

    For USAans, chips here are what you call fries.

    Graham
     
  9. Guest

    Nah, you forgot Skybuck Flying ...
    Take away the "s" and you're left with LAUGHTER, which is how you
    should look at it.
     
  10. Eeyore

    Eeyore Guest

    Not to the USA. Mainly Asia. North Africa was intersting too as was Scandinavia.
    I fancy doing Iceland some time too.

    Graham
     
  11. Rich Grise

    Rich Grise Guest

    I saw some travelogue where they showed a fish & chips stand, and it
    was big chunks of potatoes (like we'd call "steak fries") and big chunks
    of some white fish, served in a cone of newspaper, and incredibly greasy;
    If I ever have an opportunity to see England, I'd like to try some. ;-)

    (Yes, I like greasy food - Need to keep that ol' cholestrol count up in
    the "normal" range so I don't wither away! ;-) )

    Cheers!
    Rich
     
  12. You forgot their, there and they're.

    GG
     
  13. Paul G.

    Paul G. Guest


    In your quest for vaccuum tube weirdness, look into the behaviour
    of 6AR8 / 6JH8 / 6ME8 / 7360. These tubes use two electrodes that
    steer the current between two adjacent plates. That allows you to
    generate balanced modulation and other interesting effects.
    Check this site: http://www.cgs.synth.net/tube/beam.html . Eric
    Barbour has some interesting audio applications for some of these
    strange tubes.
    Check out the 6BN6, my old RCA tube manual doesn't say much about
    it, but at heart it's a very weird little tube, and it's used for FM
    quadrature detection, a neat little trick that was exploited in
    probably millions of tube TV sets. Check out:
    www.clarisonus.com/Archives/TubeTheory/6BN6_part_1.pdf and
    www.clarisonus.com/Archives/TubeTheory/6BN6_part_2.pdf
    If you thought tubes were pretty simple, the above articles will
    change your mind! They play around with the "space charge".
    There's a gold mine of info in the www.clarisonus.com/archives .
    There are a number of vendors selling audio special effects boxes that
    incorporate the 6BN6.

    Paul G.
     
  14. Rich Grise

    Rich Grise Guest

    Haven't you figured out that JS doesn't _want_ to know the facts?

    Thanks,
    Rich
     
  15. Eeyore

    Eeyore Guest

    <chuckle> And I thought he'd even made some rational comments recently. (not
    Skybuck that is) ;~).

    Graham
     
  16. Eeyore

    Eeyore Guest

    Where in India ? Be prepared to see some things that may shock, although the
    tourist destinations are pretty clear of that stuff.

    BIG tip: if you start giving the beggars money you will collect them like flies.

    Graham
     
  17. Eeyore

    Eeyore Guest

    Oh it's not *that* greasy at all. It's cooked in vegetable oil and generally
    the oil is allowed to drain well before serving.

    It has to be clean new white paper now too.

    Don't forget the vinegar and salt on the chips.

    Graham
     
  18. rex

    rex Guest

    How about the random and interchangable use of then and than. That's the
    one that drives me nuts, and from people I wouldn't expect.

    If you think their ever going to change there ways than your more
    optomistic then me.

    Make's me want to go neucular.
     
  19. rex

    rex Guest

    I think its the fault of those special interest's and earmark's in
    Warshington.
     
  20. It's the fault of the unions and other socialists dumbing-down the
    schools.

    Vote None of the Above:
    http://www.bobbarr2008.com/
     
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