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979RE: [loopantennas] Re: Transmitting loop

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  • W1EOF
    Aug 2, 2005
      Henry - Sorry but I have to disagree on your explanation of how the
      protection circuits work: Cutting back power does absolutely nothing to
      adjust the SWR down. All it does is attempt to lower the power so that the
      devices max power is not exceeded. SWR is a ratio of forward to reflected
      power. Lowering the power output from the radio will not change that ration
      one bit.

      Like any other circuit, there are compromises. They don't want the
      protection circuit kicking unnecessarily so the trigger has a time constant.
      If a pulse comes along that's great enough, and fast enough, you *WILL* lose
      your finals. This is way it's always always a good idea to disconnect your
      radios from the antenna when they are not in use.

      SWR on transmission lines is a complicated topic. For simplicity sake, you
      want to keep your SWR on coax lines as low as possible. Down in the area of
      1.5 or 2.0 to 1 is good. Look at the loss tables to see what happens at a
      particular frequency as your SWR climbs. You can easily lose 50% or more of
      your power before it reachs the antenna. Problem generally gets much worse
      as frequency goes up.


      73,

      Mark W1EOF

      -----Original Message-----
      From: Henry Kolesnik [mailto:kolesnik@...]
      Sent: Tuesday, August 02, 2005 5:12 PM
      To: loopantennas@yahoogroups.com
      Subject: Re: [loopantennas] Re: Transmitting loop


      Richards
      Any solid state rig purchased in the last 25 years hs automatic power
      reduction so the power output will depend on the SWR the rig's finals see
      and it will cut back power so that the SWR is always less than about two or
      three to one.
      ----- Original Message -----
      From: Richards
      To: loopantennas@yahoogroups.com
      Sent: Tuesday, August 02, 2005 3:36 PM
      Subject: Re: [loopantennas] Re: Transmitting loop


      I am a novice just studying for the first exams.... I gather you
      guys are in agreement on one thing...

      Whether or not you fry your output transistor, having that big
      standing wave really sucks... right?

      ///////////// Richards /////////////////
      ===========================================

      dldorrance wrote:

      >Hank, thanks for the distinction. However, even if the wave is
      >re-reflected (back and forth around the speed of light about
      >


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      If you've got links, post them in the Links section!
      http://groups.yahoo.com/group/loopantennas/links

      For uploading images, I prefer the Files section since Photos only allows
      everyone (except the uploader and moderators) to see a max of 300x400.
      http://groups.yahoo.com/group/loopantennas/files

      Put them in the appropriate folder, or create one.



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      YAHOO! GROUPS LINKS

      a.. Visit your group "loopantennas" on the web.

      b.. To unsubscribe from this group, send an email to:
      loopantennas-unsubscribe@yahoogroups.com

      c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of
      Service.


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