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20W Amplifier update + PA/Filter board for sale

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  • applewiz67
    Hi Group, I have received the Issue B boards for my 20W amplifier and they look fine. See: http://www.robbie.nildram.co.uk/main/Amp4.html ..for status blog. I
    Message 1 of 4 , Jun 1 11:23 AM
      Hi Group,

      I have received the Issue B boards for my 20W amplifier and they look fine. See:
      http://www.robbie.nildram.co.uk/main/Amp4.html

      ..for status blog. I hope to offer a kit based on the new boards in about a month.

      Also I have a spare 30m/20m PA + Filter kit which is built and tested. Not required now I have the 9V1AL motherboard. If anyone wants to buy one, email me off list. The price will be $25 + postage.

      Cheers,
      Rob (M0RZF)
    • drmail377
      Will the final version of your amplifier be suitable for use with digi-modes like PSK31. For example, if I m not mistaken PSK31 requires a linear amplifier
      Message 2 of 4 , Jun 2 4:05 AM
        Will the final version of your amplifier be suitable for use with digi-modes like PSK31. For example, if I'm not mistaken PSK31 requires a linear amplifier (such as in class-A) driven in the linear region or the signal will splatter. Refer to:

        http://aintel.bi.ehu.es/psk31theory.html

        At first glance I see no provision for ALC. Is this not required with the likes of the Softrock RxTx 6.3, especially across all bands? Without ALC how do you know you're not over-driving the amplifier?

        73's David

        --- In softrock40@yahoogroups.com, "applewiz67" <robbrown@...> wrote:
        >
        > Hi Group,
        >
        > I have received the Issue B boards for my 20W amplifier and they look fine. See:
        > http://www.robbie.nildram.co.uk/main/Amp4.html
        >
        > ..for status blog. I hope to offer a kit based on the new boards in about a month.
        >
        > Also I have a spare 30m/20m PA + Filter kit which is built and tested. Not required now I have the 9V1AL motherboard. If anyone wants to buy one, email me off list. The price will be $25 + postage.
        >
        > Cheers,
        > Rob (M0RZF)
        >
      • applewiz67
        To clarify, the spare PA/Filter board is $25. It s RxTx V6.3 compatible. Sorry for my bad grammar checking. -Rob
        Message 3 of 4 , Jun 2 4:10 AM
          To clarify, the spare PA/Filter board is $25. It's RxTx V6.3 compatible.

          Sorry for my bad grammar checking.

          -Rob
        • applewiz67
          Agreed, But it s upto the individual to set their output level appropriately. Very few amateur kit amplifiers have ALC, and mine does not. If driven at 15W PEP
          Message 4 of 4 , Jun 2 4:55 AM
            Agreed,

            But it's upto the individual to set their output level appropriately. Very few amateur kit amplifiers have ALC, and mine does not. If driven at 15W PEP output, I found my design to have a clean signal using PSK31. Adding an ALC to cope with all possible modes would increase the price substantially.

            Circuits using Mitsubishi MOSFETs are a lot cleaner than those using IRF510s. The Mitsubishi are purpose designed for HF linear amplifiers.

            Overdriving the 1W standard Softrock will produce bad intermodulation, whatever follows it.

            -Rob


            --- In softrock40@yahoogroups.com, "drmail377" <drmail377@...> wrote:
            >
            > Will the final version of your amplifier be suitable for use with digi-modes like PSK31. For example, if I'm not mistaken PSK31 requires a linear amplifier (such as in class-A) driven in the linear region or the signal will splatter.
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