Which radio goes to which antenna?

Discussion in 'Hangar Talk' started by SixPapaCharlie, Nov 16, 2017.

  1. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    How can I determine which radio is using the top antenna and which is using the bottom?
     
  2. SkyDog58

    SkyDog58 Touchdown! Greaser!

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    Old dog w/o new tricks
    The top radio in the rack uses the top antenna. That’s why it’s on top. Duh!

    To be honest, an ohm meter might be the best way to check unless you can physically trace the cable.
     
  3. Capt. Geoffrey Thorpe

    Capt. Geoffrey Thorpe Touchdown! Greaser!

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    Disconnect one antenna and see which radio has an issue receiving. However, I wouldn't touch the push to talk button with the antenna disconnected.

    And, I'm sure that this is somehow a violation of some regulation or another.
     
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  4. CMongoose

    CMongoose Pre-takeoff checklist

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    A good flashlight, an inspection mirror and tracing the cables up behind the panel
     
  5. eman1200

    eman1200 Touchdown! Greaser!

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    any reference to the installation in your logs/paperwork?
     
  6. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    No I think they built the plane around these radios. I will double check though.
     
  7. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    Funny, they built my plane around an interior lighting dimmer rheostat.
     
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  8. Clark1961

    Clark1961 Touchdown! Greaser!

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    I have it on good authority that Piper had a jig which held the master switch in place as the aircraft was assembled around it. the dimmer is immediately adjacent to the master so it's easy to believe that it is the center of an Arrow.
     
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  9. Ravioli

    Ravioli Final Approach

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    I may have been misinformed.

    I thought antennae point towards their source... so comm, marker, transponder would always be on the bottom, NAV would always be horizontal on the tail (or in wing for my RV), GPS on top.

    Of course the ADF violated that rule, but I don't think you have that on either of your planes.
     
  10. mkosmo

    mkosmo Pattern Altitude

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    Unless you like spending frivolous money... then hit the PTT.
     
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  11. Clark1961

    Clark1961 Touchdown! Greaser!

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    Cezzna and Piper typically put the com antennas on the top of the aircraft. Cezzna on the wing and Pipper on the fuselage slightly aft of the front two seats.
     
  12. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    I'm not sure I follow.
    Actually I'm certain I don't follow

    My antennas all point backwards. Explain it differently and I will try again.
     
  13. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    Ok. what happens if you hit the PTT w/ the antenna off?
    This is important because had I removed an antenna, I would have totally pushed it while checking the radio.
     
  14. mscard88

    mscard88 Touchdown! Greaser!

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    Been in situations where we couldn't receive ATC using the top antenna, so switched to the other radio (bottom antenna) and could then transmit/receive ATC. Most of ya know this, but some may not, so a good thing to know IMO.
     
  15. eman1200

    eman1200 Touchdown! Greaser!

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    "up" or "down", not forward/backward/sideways
     
  16. mkosmo

    mkosmo Pattern Altitude

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    The moral of the story is the part that makes the radio make noise in somebody else's radio will no longer have magic smoke.

    Serious: Most modern (non-aviation) radios have protection against this particular idiot move, but I don't know if any aviation radios do. If it doesn't protect itself, you burn out the transmitter portion of the radio.
     
  17. eman1200

    eman1200 Touchdown! Greaser!

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    maybe I should'a just said "top" or "bottom"
     
  18. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    No. I have Sirius/XM in both. So don't need it.
     
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  19. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    derp! Thank you for splaining.
     
  20. mscard88

    mscard88 Touchdown! Greaser!

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  21. Ravioli

    Ravioli Final Approach

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    Which side of the cable is easier to access?

    You'll want to remove one side (radio or antenna) and then see if you can RECEIVE from your handheld. (like said earlier... don't try to transmit from the potentially disconnected radio)

    Then test the other...
     
  22. FlySince9

    FlySince9 En-Route

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    IIRC...The voltage is reflected back to the transmitter, and could even be double its value or more when it reaches the transmitter...
     
  23. mkosmo

    mkosmo Pattern Altitude

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    The RF energy entirely, not just the voltage.

    If you want to key a radio without an antenna, attach a dummy load to absorb that RF.
     
  24. Van Johnston

    Van Johnston Line Up and Wait

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    No, AA-5's are build around the cigarette lighter fuse.
     
  25. eman1200

    eman1200 Touchdown! Greaser!

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    I thought grummans were built around a puddle of water?

    "Hey look, a puddle of water!"
    "Quick, put a sliding canopy over that!"
     
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  26. jsstevens

    jsstevens En-Route

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    It's because of all the great carrier based planes they built...
     
  27. SixPapaCharlie

    SixPapaCharlie May the force be with you

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  28. jsstevens

    jsstevens En-Route

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    [​IMG]
    Did you pull the red handle?
     
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  29. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    I am thinking about converting the Grumman to a fish tank.
    It's so full of water all the time. I should have listened.
     
  30. bnt83

    bnt83 Final Approach

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    Hold a fluorescent bulb near the antenna while transmitting.
     
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  31. mscard88

    mscard88 Touchdown! Greaser!

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    Just to pile on Bryan....

    [​IMG] [​IMG]
     
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  32. SixPapaCharlie

    SixPapaCharlie May the force be with you

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    I feel like I am being setup...
    Will it really react?
     
  33. mscard88

    mscard88 Touchdown! Greaser!

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    No one would do that to you.....

    [​IMG]
     
  34. Zeldman

    Zeldman Final Approach

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    Your antennas point backwards because you are flying too fast.....
     
  35. Clark1961

    Clark1961 Touchdown! Greaser!

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    Eventually. Probably works better with a SPY-1 or similar but you’ll go blind if you are holding the bulb.
     
  36. jsstevens

    jsstevens En-Route

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    I don't know if the transmitter in a airplane comm is strong enough, but rest assured a strong enough transmitter will light a fluorescent bulb. When I was a lad, my dad bought my mom a microwave oven for Christmas. Since 1) he was an electrician and 2) we had 12" fluorescent tubes around, he put one in the oven. It lit right up. Then he put a neon bulb based tester in the oven. It lit. Once. Like a flashbulb.

    Also we wired a hangar at the local airport. When the radar antenna swung around it would make the 8' tube we were carrying across the apron glow. Not exactly fully light but definitely glow.

    John
     
  37. 455 Bravo Uniform

    455 Bravo Uniform Pattern Altitude

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    If you have a regular ol FM radio, set it up next to an antenna, put it on a station in the 107 end of the spectrum, and key the mike (put your comm radio on the lower end, 118) .

    Then put it next the other antenna and key the same radio mike.

    The one on which you get the most bleed over is your antenna.
     
  38. mkosmo

    mkosmo Pattern Altitude

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    With enough power, yes. RF can excite a fluorescent light. A common demo is to put one in front of a radar dish and watch it light up.
     
  39. idahoflier

    idahoflier Pre-takeoff checklist

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    10 - 15 watts @ 118 Mhz? Not a chance...
     
  40. FlySince9

    FlySince9 En-Route

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    Did I miss something? Your canopy is leaking? Really?
     
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