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572B Tubes

Discussion in 'Amateur Radio Amplifiers' started by NA1S, Apr 17, 2021.

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  1. NA1S

    NA1S XML Subscriber QRZ Page

    I am looking to replace my 811As with 572Bs. Anyone have a recommendation as to which maker has the better parts?
  2. N6QWP

    N6QWP Ham Member QRZ Page

  3. W9JSW

    W9JSW Ham Member QRZ Page

  4. W4NNF

    W4NNF XML Subscriber QRZ Page

    I just don't know OM. I've thought about doing this a time or two. But even if you can get a set for a 100 bucks a tube.... By the time you replace could be a good ways to a used amp--like maybe an AL80b--with more robust tubes. Because of that, I press on with 811as. I did tell the XYL quite a while back that if I lose another one I'll think about a new amp. But they stubbornly keep working. :D
  5. N6QWP

    N6QWP Ham Member QRZ Page

    CTR Engineering IS W8JI's BUSINESS COMPANY. Best testing and guarantee out there. All the Chinese 572B's come from the same plants. Tom is the best source for reliable tubes. He thoroughly tests every tube
    NA1S likes this.
  6. G3YRO

    G3YRO Ham Member QRZ Page

    You don't need to replace all 4 . . .

    Just TWO 572Bs in an AL-811H will give pretty much the same power as four 811As. (and be much more reliable . . . I find the 811As flash over all the time in these amps)

    Roger G3YRO
    KG7QJB likes this.
  7. NA1S

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    I think there was an arc or flashover at some point. The amp worked fine when I put it away for the week. Blew a fuse at turn on a week later.
  8. NA1S

    NA1S XML Subscriber QRZ Page

    I hear ya on this one. I should have gone for the AL80B from the start. Coulda, woulda, shoulda......
  9. W4NNF

    W4NNF XML Subscriber QRZ Page

    I've thought the same a time or two...but the 811H has been just fine really. One tube expired a few years down the line, but I replaced it (and the meter protection diode, natch) and it's been fine since. I really only use an amplifier for phone and frankly don't work much phone, anyway. I suppose if I had to get another amp, I might look at the Acom 1010, but unless I have further problems with the old 811, I suppose I'm good. :)
    NA1S likes this.
  10. N6QWP

    N6QWP Ham Member QRZ Page

    Hi Roger--Wouldn't two 572B's in a straight AL-811 yield the same as in the H model? Same power supply. Any other changes needed? Thanx for your experience.

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