First Homebrew HF power amp

Discussion in 'Amateur Radio Amplifiers' started by N7GTB, Jan 9, 2012.

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  1. WA7PRC

    WA7PRC Ham Member QRZ Page

    I'm quite ABLE but UNWILLING to "discuss" this with you.

    Finito (meaning, I won't be revisiting this thread again).
  2. KM1H

    KM1H Ham Member QRZ Page

    I guess thats better than having to admit making a mistake or accepting that there are other valid opinions in your eyes....SOP.
  3. W9GB

    W9GB Ham Member QRZ Page

    SIMPLIFICATION for the DIY Builder of the various Regulation, Control, Monitoring, and Display electronic circuits
    of the RF Power vacuum tube operation in the linear RF amplifier.

    There are 2 well known suppliers for control boards (DIY Builders):

    One is Paul Hewitt, WD7S - who offers a Triode Control board as well as many other
    assemblies/modules (band switchable tuned input) for the DIY Builder

    The other is G3SEK/GM3SEK in the UK, who offers a Triode and a Tetrode Control board (as well as kit of parts and board).

  4. N7GTB

    N7GTB Ham Member QRZ Page

    I stumbled into a few 811a's for not too much out of pocket... I also made a concerted effort to dig into my junk boxes...found ceramic sockets, and some other parts that I think might work. I'm intrigued by this and have decided to start working on it. I've also sent away for a Russian tube (GS35B). Once I have more time (this summer or next fall) I'll begin building around that tube as well...

    I don't know if I'll manage 6 811As, but for the sake of argument seems like some increased airflow might be required...(?) 6 bottles in tandem sounds cool as all get-out. :cool:
  5. SM0NOR

    SM0NOR Ham Member QRZ Page

    Great that you going for the 811a's! It would be great to know how it advances for you. Post some pics of the progress. Here is my 811 build: (almost done):

  6. W8JI

    W8JI Ham Member QRZ Page

    Good luck on that.

    Four tubes require neutralization and barely work on ten meters.

    Unless you plan on staying below 20 meters, I'd limit to 4 tubes.
  7. N7GTB

    N7GTB Ham Member QRZ Page

    Shouldn't be too much of a problem... I seldom go up to 10m, and when I do my beam seems to get me anywhere I want to go. It's the lower bands where I would like the boost. 160m in particular is always a struggle... As I said, 6 tubes may be a bit much. By my calculations, the filaments alone will require 24 amps and I still need to come up with a suitable plate transformer for even four 811As.
  8. KA9UCN

    KA9UCN Ham Member QRZ Page

    I built a 6 tube 8-11 amp 25 years ago and was very happy with it at 15 and down. It did work on 10 but had problems. I just used it on 15 and down. It produced as expected with 1500 volts on the plate for an easy 750 watts and a stretch to hit a KW.
  9. N7GTB

    N7GTB Ham Member QRZ Page

    Great looking amp! I see the schematic for the power supply... do you have one for the amp that you'd be willing to share ?
  10. N7GTB

    N7GTB Ham Member QRZ Page

    Joe... Sent you a PM...
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