GOOD CW low powered amp suggestions to replace 811H

Discussion in 'Amateur Radio Amplifiers' started by W9RAC, Nov 17, 2019.

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  1. W9RAC

    W9RAC Platinum Subscriber Platinum Subscriber QRZ Page

    Im looking for a new dedicated amp for CW. I would like it to be reliable in the 300/350W range. Matters to me not if solid state or tube. I have been using a 811H but it has been eating tubes even at 25W input max. Time to move on.......... tnx, Rich
     
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    Better tubes may be cheaper.

    Good Luck.
     
    W9RAC likes this.
  3. W9RAC

    W9RAC Platinum Subscriber Platinum Subscriber QRZ Page

    I wondered about that but the 811a tubes seem to be a problem. Do you think 572's would cure a problem with that 811H, using it as a low power amp, OR ditch the amp in a CW environment and find a better one. That is to say, 25 ish watts in, I use tuner and dedicated antennas. Im on my second set of 811's in 1.5 years. tnx, Rich
     
  4. KA9JLM

    KA9JLM Ham Member QRZ Page

    Yes I do think the 572 would be much better, But a bit pricey.

    A home brew 4CX250B amp would be great also.
     
    W9RAC likes this.
  5. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Swapping to 572Bs would almost certainly resolve your tube life problems particularly if you're only running the amp at 350 watts or so as you mentioned in the first post. Swapping to 572Bs won't give you any more power out but it will definitely give you more robust tubes and is likely a lot more cost effective than buying a new amp.
     
    W9RAC likes this.
  6. W9RAC

    W9RAC Platinum Subscriber Platinum Subscriber QRZ Page

    I think I'll give that a try. I run that 811H with 25 watts in CW which generally yields 350 ish out, plenty for me. Thanks for the information. 73 Rich
     
    KJ6ZH likes this.
  7. W9RAC

    W9RAC Platinum Subscriber Platinum Subscriber QRZ Page

    Thanks for input. RAC
     
  8. G3YRO

    G3YRO Ham Member QRZ Page

    I agree . . .

    And just two 572Bs would be all you need . . . and at that power level they would last forever !

    Roger G3YRO
     
  9. K1LKP

    K1LKP Platinum Subscriber Platinum Subscriber QRZ Page

    RICH,

    THE DEATH RATE OF YOUR 811A TUBES IS RATHER ODD.

    IS THIS A BRAND NEW AMP THAT YOU PURCHASED OR WAS IT OWNED BY SOMEONE ELSE???

    RICH,

    CHECK OUT THIS PAGE AND BE SURE TO READ THE ENTIRE ARTICLE.

    https://owenduffy.net/tx/AL811H/index.htm
     
    Last edited: Nov 18, 2019
  10. W9RAC

    W9RAC Platinum Subscriber Platinum Subscriber QRZ Page

    I purchased it new 1.8 years ago. When the first set went I was concerned so I shipped it to Ameritron to have them check it out. They replaced a resistor and 4 tubes which they said were shot, had holes in them lasted a year. OK, so I got it back and been using it since 2/19, CW only, 25 watts max with tuner and dedicated dipole. So those lasted since Feb. then poof, gone again. I packed it up and sent it back to Ameritron Thursday they should have it tomorrow. I think it has a problem someplace causing the tube issue. Not sure but something ain't right! I'm not sure I want to invest in the 572's at this point. I may just have them fix it and move on to something that might be better for CW. I have a Alpha 8410 and a Acom A2100 but I like a small amp for CW. 73 Rich
    ps. I did read that from your post earlier so I just may move on the a different amp.
     

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