Tube ID

scubalabscubalab Posts: 2,815
I was helping my Mom clear out my grandmother’s house (she’s been in assisted living for a couple years now). I came across this tube and was wondering if anyone knows anything about it. I may just keep it as a ‘decoration’, but curious what it might have been for.

On the top, it says:

33
GY7A
USA

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Comments

  • mhardy6647mhardy6647 Posts: 23,454
    edited October 20
    heh, heh, heh. From the dark, last days of vacuum tubes. That, ol' son, is a Compactron from a series-string (transformerless "killer" circuit) television set.

    33GY7 is/was a combination diode and power pentode requiring 33 volts to light the filament.
    gxegahm9r0ko.png

    The power pentode could be used in a linear amplifier (CB radio heater or a more legitimate ham radio linear) or as an audio output tube... but not without considerable effort. B)

    That one does appear to have been used.


  • scubalabscubalab Posts: 2,815
    Thanks Mark! I knew I could count on you for some Ed Jucashun.

    Yeah, definitely looks used (bad) as it’s got two ‘hot’ marks on it. Didn’t want to throw it out, but wanted to be able to tell folks what it is when they see it, maybe hanging from the Christmas tree!
  • pitdogg2pitdogg2 Posts: 14,715
    hot spots are common in tubes, it in itself usually is not an indicator on whether or not it's bad.
  • mhardy6647mhardy6647 Posts: 23,454
    edited October 21
    scubalab wrote: »
    Thanks Mark! I knew I could count on you for some Ed Jucashun.

    Yeah, definitely looks used (bad) as it’s got two ‘hot’ marks on it. Didn’t want to throw it out, but wanted to be able to tell folks what it is when they see it, maybe hanging from the Christmas tree!
    pitdogg2 wrote: »
    hot spots are common in tubes, it in itself usually is not an indicator on whether or not it's bad.

    Indeed, it is exactly as @pitdogg2 says -- not necessarily bad at all; it's just a marker that indicates the tube's not brand new. Those are tubes that run very hard in their intended applications. They're built for it (rough and tough), but they will show signs of use... as that one does.

    As long as you don't have -- oh, I dunno -- a 1960s GE "Portacolor" TV that needs one, you may never know! ;)

    Heck, I have a "Portacolor" in the basement... someplace... :p
    (the only all vacuum tube TV in the house... believe it or not)


    PS -- connect somewhere on the order of 33 volts (AC is OK) to pins 1 and 12 and you can use it as a lighted Christmas ornament. :#

    You wouldn't be the first...
  • scubalabscubalab Posts: 2,815
    I just assumed it was bad, since it definitely looked 'used'. I assumed it was from an old TV or Radio my grandfather had. I assumed 'bad', like he replaced it with a new one and put the bad one in the box and never threw it out. Heck, it could still be 'good'. I just thought it was too cool to throw out. I'll likely display it in a music-related setup. Or, a lighted Christmas ornament. ;)
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