Replacement of RCA 8122 Tubes

Discussion in 'Amateur Radio Amplifiers' started by N2OTG, Jul 12, 2015.

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  1. KM1H

    KM1H Ham Member QRZ Page

    Time to replace the parasitic suppressor resistor for both tubes for starters.

  2. N2OTG

    N2OTG Ham Member QRZ Page

    We replaced one already, since it was charcoal... why replace the other one?
  3. AF7XT

    AF7XT Ham Member QRZ Page

  4. KM1H

    KM1H Ham Member QRZ Page

    They go way up in value over time and become useless
  5. AF7XT

    AF7XT Ham Member QRZ Page

    "parasitic suppressor failure due to extended key-down use on ten meters"
    CSB 66-4
    Page 3
    July '66
    (from memory Carl , did I get that right ?)
    I'm sure we can find a pic of the updated suppressor around somewhere if you need it .
  6. KM1H

    KM1H Ham Member QRZ Page

    I believe you Dennis and that saves me looking for it in the "tons" of National paper Ive accumulated. I generated my share of it including that one which was the result of a 48 hour DX contest when the sunspots were fine for 10M. Lost about 30 minutes of contesting to build and test (thanks to a well stocked shop at home) and they are still in place. That is the amp I later added 160 plus went with a new plate choke that allowed 12 and 17M.

  7. AF7XT

    AF7XT Ham Member QRZ Page

    Had it tucked away in a backup :)

    via W7CPA , zoom in an the mod is easy to see. In the pic Randy used metal film but at last note was changing to old school carbon.

    Attached Files:

    • n.pdf
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    Last edited: Apr 5, 2018
  8. K8ROY

    K8ROY Ham Member QRZ Page

    following . I just acquired a NCL200 myself
  9. KM1H

    KM1H Ham Member QRZ Page

    That amp is too pretty to go to scrap when there are several alternatives to keep it running.

    Many thanks again to Reid Brandon for providing actual first hand histories of Eimac and RCA instead of just repeating what others said.

  10. KD5OEI

    KD5OEI Ham Member QRZ Page

    Carl, what is your opinion of the NCL-2000 blower? Mine is in good working order so I suppose it is adequate, but I think it's smallish. OK I think most blowers are too small. I sometimes use the amp for AM but only with about 100W carrier and the usual 100% modulation.

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