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572B Tubes

Discussion in 'Amateur Radio Amplifiers' started by NA1S, Apr 17, 2021.

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  1. G3YRO

    G3YRO Ham Member QRZ Page

    Absolutely !

    And the big advantage is that 572Bs would never flash over in these Amps. as they are rated for a much higher HT Voltage.

    When the 811As flash over, it's not just that they destroy that Valve . . . it's all the other components they take out, that are a real pain to get at in these Amps . . . especially the cheap sealed plastic relays in the later ones.

    Roger G3YRO
  2. K4PDM

    K4PDM Ham Member QRZ Page

    I would trust W8JI, but RF Parts has a good reputation too, and the 572Bs they are selling now look exactly like the ones from Command Technologies.

    I just bought a matched set of 4 for my old Clipperton L and get 700-800 watts output with 25 watts drive. SSB hits 1KW with 40 watts drive.

    The plate is much thicker and the glass envelope is bigger than the weak Svetlana tubes I replaced. The new tubes look a whole lot like my old Cetrons.
    KO4DN and NA1S like this.
  3. KG7QJB

    KG7QJB XML Subscriber QRZ Page

    Is the issues mainly due to running the amps too hard or near max. I just purchased a used 811 H from a local who used it pretty sparingly. I have not hooked it up to my Yaesu FTDX 1200 as of yet. He did put in new Taylor 811's about a year ago. I am wondering if I should just sell it or hook it up with the 704 relay I got with it. I also have an Icom 7300 with a Yaesu FL2100B hooked to it. I push it gently with 60 watts input to help me get out when conditions are tough but find myself mainly running just what the radios put out . Any advice is appreciated.
  4. G3YRO

    G3YRO Ham Member QRZ Page

    I don't think so . . . all the Amps I have repaired for people say they have just flashed over on Standby, or when turning them on.

    It just seems like the HT voltage in these Amps is too high for some of the 811A valves.

    The Yaesu amps are a much more solid design (they make the Ameritrons look like they're homebrew!) I ran one one for 35 years, and never had a fault.

    Roger G3YRO

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