3-500 Tube Life

Discussion in 'Amateur Radio Amplifiers' started by VK4TUX, Dec 2, 2011.

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  1. VK4TUX

    VK4TUX Ham Member QRZ Page

    I am wondering what is the best voltage to run on some TL922 socket cathode connections here,
    and what is optimum for; life span , power output & reliability rate of the tube.
    I have a spare set too, I guess it would be better to rotate them yearly rather than leave one set on the shelf for may years etc.

    A.Fewster ... vk4tux
  2. W8JI

    W8JI Ham Member QRZ Page

    Tube failures from filament voltage are virtually unheard of. If you really want to be fussy though, set the tube to run nominal rated voltage, 5.0 volts, at your middle line voltage range. That's what Eimac says to do for all of their tube, so it probably would apply to other similar tubes.
  3. KA7JUN

    KA7JUN Ham Member QRZ Page

    There was an article in Oct '11 QST magazine on this. I don't have it here with me but I believe it was 4.8-5v and it showed how he accomplished that.
  4. PA5COR

    PA5COR Ham Member QRZ Page

    4.75 to 5.25 volts.
    Don't set it too low, when the amp runs power your grid will drop too, so you actually could get to the point that the filament is fed below the 4.75 volts...

    Mine in the Heathkit SB-1000 is at 5.1 volts without the amplifier in use 3100 volts.
    Stiff 230 volts 50 Hz 16 Amp house circuit.
    I did build in the soft start which takes just under a second to come up to full power.
    Might be better for the inrush of the filament current too.
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    There was considerable discussion of that article here back in October.
    That article not only contained misinformation but the test methods and equipment employed were not correct and the conclusions drawn were wrong. The league dropped the ball regarding technical review.
  6. K0BG

    K0BG Ham Member QRZ Page

    There is a slight blurb about it in a subsequent issue, and supposedly a whole article coming in the January issue with the intent of correcting the data.
  7. AF6LJ

    AF6LJ Ham Member QRZ Page

    I must have missed the bit in the November issue.
    Typical lets make the retractions as hard to find as possible.
  8. WA6TKD

    WA6TKD Ham Member QRZ Page

    I know bumbkis about large power tubes. Would using a high current 5vdc regulated power supply for the filament be a useful 'solution"? Or does using DC voltage Vs AC shorten filament life?

  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    It's "bupkis":eek:

    Yiddish for "beans"

  10. WA6TKD

    WA6TKD Ham Member QRZ Page

    Sorry I'm non-religious and my spell checker was of no help for the term, I did check. :eek:

    So what of my question about using DC for filament voltage? Do moble ham tube type amplifiers use AC for their filaments?

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