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Chinese 811A "Power Amplifier" Tube from Amazon ??

Discussion in 'Amateur Radio Amplifiers' started by K4ZOT, Dec 20, 2018.

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  1. AI3V

    AI3V Ham Member QRZ Page

    By buying with opm - other peoples money- you can't loose.

    I order with an American Express card thru PayPal,

    I have a 100% record getting my money refunded when items do not work as advertised.

    Rege
     
  2. KD8DEY

    KD8DEY Ham Member QRZ Page

    In reference to OPM....
    I would have considered upgrading to 572B's in the amp if I was in the market for replacement tubes...
     
    K6LPM, K1JFJ and AI3V like this.
  3. K4ZOT

    K4ZOT XML Subscriber QRZ Page

    Update: Well, about 6 weeks of nearly daily use and the Chinese audio 811A tubes are still putting out 400 watts FT8. This is a real bargain at Amazon over the other priced tubes on the market.
     
    W1TRY likes this.
  4. G3YRO

    G3YRO Ham Member QRZ Page

    Well I have bought several 572Bs direct from China on eBay . . . and always found them excellent.

    If you think the price of the same valves from RF Parts is expensive in the USA, you want to see how much they charge to ship them to the England ! (whereas shipping from China is virtually nothing)

    Also . . . regading "Audio" or "RF" versions of these valves . . . do you really think the factory would make TWO different versions?! Why on earth would they ?!

    Roger G3YRO
     
  5. N8CMQ

    N8CMQ XML Subscriber QRZ Page

    audio toobs sound warmer Roger, just ask any audiophool!
     
  6. N8FVJ

    N8FVJ Ham Member QRZ Page

    Russian G811 tubes on ebay are about $20 each in NOS and are reported to be better made than Chinese built 811As.
     
  7. VK2WP

    VK2WP XML Subscriber QRZ Page

    Am running Russian G811's in my 811H and they are excellent value, far better than the Chinese 811A.

    Noticed though stocks of the G811 seem to be running down a bit. Glad I bought two complete sets which should see me out.
     
  8. KM1H

    KM1H Ham Member QRZ Page

    Those Russian tubes are 811's and not 811A's and should be run at lower power, otherwise quality is good. None of the Chinese versions are true 811A's either, as can be seen when looking at the anode of a real USA version.

    Carl
     
    N8FVJ likes this.
  9. N8FVJ

    N8FVJ Ham Member QRZ Page

    Although the G811 is rated less power out by the Russian manufacture Ryazan vs USA & Chinese 811As, the plate is same size and has the two vertical fins like Chinese 811A and later USA manufactured 811A tubes. The RCA 811A did have six horizontal fins on each side of the plate and rated at 65 watts plate dissipation. The RCA 811 without fins were rated at 45 watts dissipation.

    The newer 811As do not have the 12 horizontal fins, but have a single vertical fin running the length of the plate on both sides. RCA 811 do not have the vertical fins. So, I suspect all 811A from China or the Russian G811 are about a true 55 watts plate dissipation per what I read elsewhere. The RCA 811A with the 12 horizontal fins are true 65 watt dissipation tubes. And, the old RCA 811A would hold off red plating during tune up much longer vs the newer vertical fin tubes.

    When quickly and properly tuned the Chinese 811A and Russian G811 operate at Ameritron factory rated output without red plating at least on 80 to 20 meters. So, you do not have to de-rate the G811 output or the Ameritron supplied Chinese 811A tubes except on possibly 15 meters and especially on 10 meters where efficiency is less.

    That being said, it is prudent to limit output less than the factory specifications on the Ameritron 811 & 811H amps. Ameritron push the power output higher for advertising reasons as did the vintage amplifier manufactures. The good news are $20 G811 tubes for sale for budget minded hams that comfortably produce (with your SSB speech processor on- higher duty cycle) 600 watts SSB with the Ameritron 811H and 450 watts SSB on the Ameritron 811 amplifiers on 80 thru 20 meters without red plating the tubes or reducing tube life.

    Want more power out? Buy an Ameritron AL80B.
     
    Last edited: Mar 22, 2019
  10. KA9JLM

    KA9JLM Ham Member QRZ Page

    Where do you get them for 20 dollars ?
     

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