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Re: [softrock40] Re: WWV 30M Antenna?

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    A 6 or 10 dB pad will force the input to 50 ohms. gfz ... From: drmail377 Subject: [softrock40] Re: WWV 30M Antenna? To:
    Message 1 of 4 , Sep 26, 2008
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      A 6 or 10 dB pad will force the input to 50 ohms. gfz

      --- On Thu, 9/25/08, drmail377 <drmail377@...> wrote:
      From: drmail377 <drmail377@...>
      Subject: [softrock40] Re: WWV 30M Antenna?
      To: softrock40@yahoogroups.com
      Date: Thursday, September 25, 2008, 10:21 PM

      Hi Robin,

      If you're in the continental U.S. and your local power-line noise
      isn't too bad, I'll venture to guess that with a Softrock receiver you
      should be able to receive at least one WWV frequency at any time of
      the day with something like ten feet feet of wire hanging out a window.

      The design of the Softrock receiver requires a 50 Ohm antenna for
      optimal operation. The receiver gain and bandwidth are roughly
      inversely proportional to antenna impedance. This is explained in
      Youngblood's four-part 2002/2003 QEX article "A Software-Defined Radio
      for the Masses" which may be freely downloaded here:

      http://www.arrl. org/tis/info/ sdr.html

      In addition to or instead of an antenna tuner as mentioned by Tom, a
      pre-amplifier may isolate some of the antenna mismatch affects. In
      your case where you mention a short antenna for WWV reception, you
      might want to try an "active antenna". Here's a page with some links
      to active antenna circuits:

      http://www.discover circuits. com/A/active. htm

      A google search for active antennas will yield a lot of links, some to
      pre-built off the shelf units. Do tell us about your results should
      you decide to move forward.

      Best 73's, David WB4ONA

      --- In softrock40@yahoogro ups.com, k5nwa <k5nwa@...> wrote:
      > At 05:39 PM 9/25/2008, you wrote:
      > >I'm wondering if any of you use your 30M Lite kit to receive WWV, and
      > >if so, how little of an antenna can you get away with?
      > >
      > >Thanks,
      > >Robin Midgett K4IDC
      > >615-322-5836 office - rolls to pager
      > >615-835-7699 pager
      > >615-301-1642 home
      > >K4IDC@...
      > >Radio Gear For Sale:
      > >http://www.people. vanderbilt. edu/~robin. midgett/index. htm
      > The input filter of the SoftRock requires a 50 Ohm resistive antenna
      > otherwise it's frequency response is shifted and the receiver is
      > pretty deaf. But if you have a tuner to make the wire look like 50
      > Ohms resistive source then a short wire will work just fine.
      > The shortest I used was 8' with a tuner to make it purely resistive
      > and it worked fine. The length you can get away with depends on your
      > Cecil
      > K5NWA
      > www.softrockradio. org www.qrpradio. com
      > "Blessed are the cracked, for they shall let in the light."

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