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  • March 12, 2020 at 9:19 pm #8295
    Mark
    Participant

    Can someone explain the difference between the output tube wiring in the book layout (from the revised book showing only one output tube) and the revised layout on the TAN website? That is, why are they different? Is the book layout incorrect?

    Also, I followed the book’s parts list and got the 1k 2W resister that connects to pin 4 in the book layout, which is absent on the TAN layout. Instead, the TAN layout uses a 1.5k resister, R11, coupling pin 5 and 6. Can I use the 1k for that (R11) instead of the 1.5k? What would the effect be? Hope I’m making sense…

    March 12, 2020 at 9:27 pm #8296
    Andy
    Keymaster

    Hey Mark,

    What printing of the book do you have? That might help someone at the network identify any discrepancies. The book most of us have used is the two tube version with the addendum that you can find on the Wiki page.

    March 12, 2020 at 9:33 pm #8297
    Andy
    Keymaster

    That R11 acts as a low pass filter to cut out radio frequencies. Some folks remove it entirely to get more gain from the power tube. So the 1K should be fine there. Here is a great resource in the whys of the grid stopper – https://www.aikenamps.com/index.php/grid-resistors-why-are-they-used

    March 12, 2020 at 9:35 pm #8298
    Mark
    Participant

    I have the 2015 version of the book that only shows 1 6V6GT tube. It’s wired differently from the TAN layout on this website. I’ll try to scan the layout and post it.

    March 12, 2020 at 11:56 pm #8299
    Mark
    Participant

    Thanks. Makes sense. Thanks for the link, I hadn’t been to Aiken’s site in years.

    March 13, 2020 at 6:55 pm #8300
    Mark
    Participant

    One other question. Why does the layout show connections to pin 1 and 6 when those pins don’t even exist and are not referenced in the schematic?

    March 16, 2020 at 2:18 pm #8313
    Andy
    Keymaster

    In the layout diagram on the site, pin 1 is connected to ground as some octals have pin 1 the shell which grounds it well. For pin 6, that is simply wired as a patch point for the 1.5K grid resistor. You could wire that directly, but for people using the 5F2A circuit layout board, it is generally a nice connection point. It helps keep wires separate and maximizes the distances between them.

    So pin 1 is a ground, pin 6 is just a “terminal” for easy connection.

    March 17, 2020 at 3:54 pm #8317
    Mark
    Participant

    Got it. Thanks!

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