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

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

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  1. K4ZOT

    K4ZOT XML Subscriber QRZ Page

    I have a Ameritron Al-811 Amp and the fuses blew on it recently. I found a bad 811A tube. The tubes are rather expensive these days. I looked on Amazon and found a Chinese 811A "power amplifier" tubes. I found several reviews from Hams that said the tubes worked fine in their Ameritron amps.

    https://www.amazon.com/gp/product/B00E0TOKVW/ref=od_aui_detailpages00?ie=UTF8&psc=1

    Just curious if anyone else has used these tubes?

    Thanks,

    Glenn
    K4ZOT
     
  2. KA0HCP

    KA0HCP XML Subscriber QRZ Page

    KI5WW, AA5CT, WE6C and 2 others like this.
  3. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'd go with RF Parts also. (Ameritron also sells 811As, and they should be fine.)

    The Amazon.com seller in the link is "Amplified Parts" who specializes in parts for guitar amplifiers and audio stuff, not RF. There have been "some" 811As and even 572Bs sold into that market that will not withstand the higher voltage used in amateur radio amplifiers including the AL-811s, which push the tubes right to their limit and a bit beyond that.
     
  4. W1QJ

    W1QJ Ham Member QRZ Page

    This is true but a good tube should hi-pot several times it's operating voltage before it shows any leakage. But I guess that is wishful thinking.
     
  5. N7WR

    N7WR Subscriber QRZ Page

    I've always had good luck with tubes from RF Parts. Many of their current 811s and 572Bs come from China. When last I heard RF Parts tests each one before they sell them
     
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    You need a good hipot tester for that. It should bear this insignia.:)
    upload_2018-12-20_11-2-26.jpeg

    I think it's really "high" pot.:p
     
    KI5WW and KA9JLM like this.
  7. W1QJ

    W1QJ Ham Member QRZ Page

    Ah-oh Steve has been hitting on that holiday punch.
     
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Nah, I was just wondering where Pat went.:p
     
    KD8DEY likes this.
  9. W1QJ

    W1QJ Ham Member QRZ Page

    You mean WA6MHZ? Oh he's around. He's a regular on Facebook.
     
  10. K4ZOT

    K4ZOT XML Subscriber QRZ Page

    The prices for two 811A tubes between RF Parts and Amazon including shipping and tax are: RF Parts - $85.84 and Amazon - $48.45. This was too much of a difference to ignore on my retirement budget. Plus there were several positive reviews on Amazon by Hams running my same Amp. Not that it means anything, but the picture of the tube matches my bad Taylor 811A that shorted out.

    One other question which has puzzled me. I only have two tubes that are lit in my AL-811 Amp - the third one is not lit. BUT, I have 350 watts out on my wattmeter? The AL-811 is rated on 400 watts CW out. If the third tube is not lit the output should be probably 250 or less.

    Glenn
     

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