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Capacitor question for group

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  • metrobase201
    I have a dual gang 365pf capacitor, it also have 2 screws trimmers on the side, Can any one explain these to me and what they do? -MetroBase 201
    Message 1 of 4 , Feb 18, 2008
      I have a dual gang 365pf capacitor, it also have 2 screws trimmers on
      the side, Can any one explain these to me and what they do?
      -MetroBase 201
    • gandalfg8@aol.com
      In a message dated 18/02/2008 15:30:47 GMT Standard Time, metrobase201@yahoo.com writes: I have a dual gang 365pf capacitor, it also have 2 screws trimmers on
      Message 2 of 4 , Feb 18, 2008
        In a message dated 18/02/2008 15:30:47 GMT Standard Time,
        metrobase201@... writes:




        I have a dual gang 365pf capacitor, it also have 2 screws trimmers on
        the side, Can any one explain these to me and what they do?






        -------------------------------------
        The trimmers are there to adjust oscillator tracking when used in a receiver.

        In these days of digital displays it's not so noticeable as it was on tuning
        scales with a pointer, but linearity of capacitor and oscillator tracking is
        always a compromise and the trimmers help to get the best fit.
        If, in a superhet receiver, one capacitor is used for a tuned RF amplifier
        and the other for a local oscillator it's also important to have a fine
        adjustment to keep them as well matched as possible over the tuning range.

        regards

        Nigel
        GM8PZR







        [Non-text portions of this message have been removed]
      • metrobase201
        ... on ... a receiver. ... on tuning ... tracking is ... amplifier ... fine ... tuning range. ... Thank you, thats probally when using my Sony 7600gr and
        Message 3 of 4 , Feb 18, 2008
          --- In loopantennas@yahoogroups.com, gandalfg8@... wrote:
          >
          >
          > In a message dated 18/02/2008 15:30:47 GMT Standard Time,
          > metrobase201@... writes:
          >
          >
          >
          >
          > I have a dual gang 365pf capacitor, it also have 2 screws trimmers
          on
          > the side, Can any one explain these to me and what they do?
          >
          >
          >
          >
          >
          >
          > -------------------------------------
          > The trimmers are there to adjust oscillator tracking when used in
          a receiver.
          >
          > In these days of digital displays it's not so noticeable as it was
          on tuning
          > scales with a pointer, but linearity of capacitor and oscillator
          tracking is
          > always a compromise and the trimmers help to get the best fit.
          > If, in a superhet receiver, one capacitor is used for a tuned RF
          amplifier
          > and the other for a local oscillator it's also important to have a
          fine
          > adjustment to keep them as well matched as possible over the
          tuning range.
          >
          > regards
          >
          > Nigel
          > GM8PZR
          >
          >
          >
          >
          >
          >
          >
          > [Non-text portions of this message have been removed]
          >
          Thank you, thats probally when using my Sony 7600gr and turning the
          screws on the capacitor I don't notice anything.
          Thanks again.
          -Metrobase
        • gandalfg8@aol.com
          In a message dated 18/02/2008 16:14:55 GMT Standard Time, metrobase201@yahoo.com writes: Thank you, thats probally when using my Sony 7600gr and turning the
          Message 4 of 4 , Feb 18, 2008
            In a message dated 18/02/2008 16:14:55 GMT Standard Time,
            metrobase201@... writes:

            Thank you, thats probally when using my Sony 7600gr and turning the
            screws on the capacitor I don't notice anything.



            ---------------------------------
            That's probably because they're much lower value than the main capacitor so
            would have very little effect.
            The adjustments I mentioned before would be carried out at manufacture and
            then left.

            regards

            Nigel
            GM8PZR






            [Non-text portions of this message have been removed]
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