Tube suggestions for 811H

Discussion in 'Amateur Radio Amplifiers' started by AC2MM, Dec 30, 2018.

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  1. N8FVJ

    N8FVJ Ham Member QRZ Page

    I believe the Svetlana used in AL-811 or AL-811H will last as long as the Cetron 572B. Svetlana will not arc over at 1500 volts plate.
     
    Last edited: Jan 30, 2019
  2. WD4IGX

    WD4IGX Premium Subscriber QRZ Page

    I may be able to run 220 to the ham shack this summer but not before.
     
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Thoriated carbonized?

    Never heard of that. Svetlana 572Bs, like all the others, use a thoriated tungsten filament...
    Svetlana 572B.PNG
     
  4. N8FVJ

    N8FVJ Ham Member QRZ Page

    Carbonized reduces thoria loss (loss emissions). All vintage power tubes with direct filamants use a carbonized tungsten filament.
     
  5. WD4IGX

    WD4IGX Premium Subscriber QRZ Page

    My point in mentioning the Svetlanas was that I thought Russian tubes were, in general, superior to Chinese tubes. If that is no longer true due to better Chinese QC, and/or not true for the 572Bs due to different designs, then it makes no sense to pay more for Svetlanas because they are "as good as" Chinese tubes.

    Sounds like the Chinese tubes are fine for AL-811s and AL-811Hs.

    BTW, running this one on that 120v circuit, even with everything else of much load on it turned off, the meter lights dim very noticeably key-down. I'll try to check the line voltage key down and see what I'm getting at that point, but I can't do much about it in any case right now. 220v to the shack is not happening before spring at the earliest, and then only if I see a real need for it. I don't think 500W vs 700W output when I really ought to only run 500 anyway for tube life is a real need.
     
  6. N8FVJ

    N8FVJ Ham Member QRZ Page

    I did not say Chinese were better tubes. I highly doubt the Chinese are better than Svetlana.
     
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    They easily could be, since the Chinese factory recently (some months ago) copied the original Cetron design including internal elements, glass type and everything else.

    Svetlana didn't.

    Svetlana is a variable. I have an engineer at work who is from the Ukraine and worked at the Svetlana plant years ago, before he came here.

    "What does Svetlana mean?" I had to ask.

    "It's a girl's name, like Ann."

    Oh.

    They made millions of tubes, some good, some not so good.
     
  8. WD4IGX

    WD4IGX Premium Subscriber QRZ Page

    I knew it was a girl's/woman's name. So many pilots here in the US are in love with Russian aerobatic pilot Svetlana Kapanina:

    Skip ahead to 9:45 for beginning of takeoff roll:



     
  9. N8FVJ

    N8FVJ Ham Member QRZ Page

    I am not sure if the Chinese tubes properly coat the direct filament with carbon. If correct, the filament would last a long time. In the past, the Chinese tubes did not last long. I think I read a few thousand hours. Cetron been reported to last 50000 hours, but who knows.
     

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