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Re: Light-Sport Aircraft Yahoo group Transponder Antenna install

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  • Helen Woods
    I don t know about legality, but I do know something about functionality. It s not going to do you much good up there. You mount a transponder antenna on the
    Message 1 of 5 , Apr 4, 2012
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      I don't know about legality, but I do know something about
      functionality. It's not going to do you much good up there. You mount
      a transponder antenna on the belly for the same reason you mount a GPS
      antenna on the roof - you want have an unobstructed view of what it is
      trying to talk with. Here in the DC SFRA we don't go anywhere unless
      ATC can pick up our transponder. Even mounted on the belly, the slant
      range, especially on a low wing plane, can cause problems with ATC
      picking up you signal. It's not uncommon for me to have to do a steep
      banked 360 especially at low altitude for them to get my signal. I
      can't imagine them ever getting my signal if the antenna was on the roof.

      Helen

      On 3/26/2012 4:11 PM, ron_d_hill wrote:
      > Is there any legal reason why I can't install my transponder antenna on the TOP of the plane between the wings?
      >
      > See, I have a challenger and the whole bottom of the plane is fabric with a few braces made out of aluminum. It seems like it would be MUCH easier to just drill a whole and install the antenna on the metal covering than making a grounding plane and riveting it to the braces under the plane.
      >
      > Also, it would move the antenna further away from the occupants.
      >
      >
      >
      > ------------------------------------
      >
      > Yahoo! Groups Links
      >
      >
      >
      >
    • A. Censor
      Hi Helen, I hope and bet that you meant you “do a steep banked turn at 60 degrees” not “at 360 “ . Either that or your capabilities and your
      Message 2 of 5 , Apr 5, 2012
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        Hi Helen,
         
        I hope and bet that you meant you  “do a steep banked turn at 60 degrees”  not “at 360 “    . <g>
        Either that or your capabilities and your aircraft are far more acrobatic than most of the rest of us. Winking smile
         
        ---------
         
        I’m not an avionics/radio guy (so take what I say next with a grain of salt) but my electronic and radio knowledge (ex-physics major and computer tech) isn’t _totally_ absent, so FWIW here’s my take
         
        Seem to me like you WANT your ELT antenna on top. Most crashed planes (the time you’d MOST hope your ELT is received) are on the ground right side up and the search planes homing on your ELT are above you.)
         
        A final thought: There’s something to be said for carrying a pocket-type PERSONAL locator beacon (PLB).
        They cost a tiny fraction of what the new aircraft ELT’s ($1000 to $3000) cost, and unlike the older ELTs that transmit only on 121.5-MHz (and are not picked up by the satellite) that many of us have in our aircraft a PBL works on the newer 406-MHz that the satellite system (NOAA Search and Rescue Satellite Aided Tracking (SARSAT) )  picks up even if you’re stuck in some steep remote valley.
        You can get a PLB for a little over $200 whether you buy at a sporting goods outlet like REI or an aircraft source like Spruce.
         
        If like, me, anyone else has one of the many older ELTs that transmit on 121.5 you might note this comment from AOPA:
        It is important to note that after 2009, existing 121.5-MHz ELTs, although still legal from the FAA's perspective, will provide extremely limited assistance if an aircraft crashes, especially in a remote location.
         
         
        As for the net pros and cons of positoining the ELT antenna  – I’d say check with folks/techs in an avionics forum:
        Just google 
                    avionics forum
        and you’ll find dozens of them.
         
        Alex
         
         
         
        "Helen Woods" Helen_Woods@... hwoods4421 Wed Apr 4, 2012 5:26 am (PDT)


        I don't know about legality, but I do know something about
        functionality. It's not going to do you much good up there. You mount
        a transponder antenna on the belly for the same reason you mount a GPS
        antenna on the roof - you want have an unobstructed view of what it is
        trying to talk with. Here in the DC SFRA we don't go anywhere unless
        ATC can pick up our transponder. Even mounted on the belly, the slant
        range, especially on a low wing plane, can cause problems with ATC
        picking up you signal. It's not uncommon for me to have to do a steep
        banked 360 especially at low altitude for them to get my signal. I
        can't imagine them ever getting my signal if the antenna was on the roof.

        Helen
        On 3/26/2012 4:11 PM, ron_d_hill wrote:
        > Is there
        any legal reason why I can't install my transponder antenna on the TOP of the plane between the wings?
        >
         
         
         
         
         

      • Bill Watson
        The initial poster asked about their transponder, which sends the 4 digit code from your dashboard to the radars tracking you (during your flight). I ve seen
        Message 3 of 5 , Apr 5, 2012
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          The initial poster asked about their transponder, which sends the 4 digit code from your dashboard to the radars tracking you (during your flight). I've seen ELT (after your flight) antennas inside the plane. Certainly since there is no way to predict what airplane skin you may have left, ELT antenna positions can vary.

           

          Bill Watson

          bill@...

           

          From: Sport_Aircraft@yahoogroups.com [mailto:Sport_Aircraft@yahoogroups.com] On Behalf Of A. Censor
          Sent: Thursday, April 05, 2012 8:38 AM
          To: Sport_Aircraft@yahoogroups.com
          Subject: {Tagged!} Light-Sport Aircraft Yahoo group Re: Transponder Antenna install

           

           

          Hi Helen,

           

          I hope and bet that you meant you  “do a steep banked turn at 60 degrees”  not “at 360 “    . <g>

          Either that or your capabilities and your aircraft are far more acrobatic than most of the rest of us. Winking smile

           

          ---------

           

          I’m not an avionics/radio guy (so take what I say next with a grain of salt) but my electronic and radio knowledge (ex-physics major and computer tech) isn’t _totally_ absent, so FWIW here’s my take

           

          Seem to me like you WANT your ELT antenna on top. Most crashed planes (the time you’d MOST hope your ELT is received) are on the ground right side up and the search planes homing on your ELT are above you.)

           

          A final thought: There’s something to be said for carrying a pocket-type PERSONAL locator beacon (PLB).

          They cost a tiny fraction of what the new aircraft ELT’s ($1000 to $3000) cost, and unlike the older ELTs that transmit only on 121.5-MHz (and are not picked up by the satellite) that many of us have in our aircraft a PBL works on the newer 406-MHz that the satellite system (NOAA Search and Rescue Satellite Aided Tracking (SARSAT) )  picks up even if you’re stuck in some steep remote valley.

          You can get a PLB for a little over $200 whether you buy at a sporting goods outlet like REI or an aircraft source like Spruce.

           

          If like, me, anyone else has one of the many older ELTs that transmit on 121.5 you might note this comment from AOPA:

          It is important to note that after 2009, existing 121.5-MHz ELTs, although still legal from the FAA's perspective, will provide extremely limited assistance if an aircraft crashes, especially in a remote location.

           

           

          As for the net pros and cons of positoining the ELT antenna  – I’d say check with folks/techs in an avionics forum:

          Just google 

                      avionics forum

          and you’ll find dozens of them.

           

          Alex

           

           

           

          "Helen Woods" Helen_Woods@... hwoods4421 Wed Apr 4, 2012 5:26 am (PDT)



          I don't know about legality, but I do know something about
          functionality. It's not going to do you much good up there. You mount
          a transponder antenna on the belly for the same reason you mount a GPS
          antenna on the roof - you want have an unobstructed view of what it is
          trying to talk with. Here in the DC SFRA we don't go anywhere unless
          ATC can pick up our transponder. Even mounted on the belly, the slant
          range, especially on a low wing plane, can cause problems with ATC
          picking up you signal. It's not uncommon for me to have to do a steep
          banked 360 especially at low altitude for them to get my signal. I
          can't imagine them ever getting my signal if the antenna was on the roof.

          Helen

          On 3/26/2012 4:11 PM, ron_d_hill wrote:

          > Is there any legal reason why I can't install my transponder antenna on the TOP of the plane between the wings?
          >

           

           

           

           

           

           

        • Mark C
          My last plane was a challenger I installed the Antenna under the plane. Use a small piece of thin sheet metal on both sides
          Message 4 of 5 , Apr 5, 2012
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            My last plane was a challenger I installed the Antenna under the plane. Use a small piece of thin sheet metal on both sides

            --- In Sport_Aircraft@yahoogroups.com, "ron_d_hill" <Ron@...> wrote:
            >
            > Is there any legal reason why I can't install my transponder antenna on the TOP of the plane between the wings?
            >
            > See, I have a challenger and the whole bottom of the plane is fabric with a few braces made out of aluminum. It seems like it would be MUCH easier to just drill a whole and install the antenna on the metal covering than making a grounding plane and riveting it to the braces under the plane.
            >
            > Also, it would move the antenna further away from the occupants.
            >
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