Which radio goes to which antenna?

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?
 
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.
 
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.
 
A good flashlight, an inspection mirror and tracing the cables up behind the panel
 
any reference to the installation in your logs/paperwork?
 
Sac Arrow said:
Funny, they built my plane around an interior lighting dimmer rheostat.
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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.
 
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.
 
Capt. Geoffrey Thorpe said:
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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Unless you like spending frivolous money... then hit the PTT.
 
Ravioli said:
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.
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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.
 
Ravioli said:
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.
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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.
 
mkosmo said:
Unless you like spending frivolous money... then hit the PTT.
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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.
 
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.
 
SixPapaCharlie said:
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.
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"up" or "down", not forward/backward/sideways
 
SixPapaCharlie said:
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.
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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.
 
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...
 
FlySince9 said:
IIRC...The voltage is reflected back to the transmitter, and could even be double its value or more when it reaches the transmitter...
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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.
 
I thought grummans were built around a puddle of water?

"Hey look, a puddle of water!"
"Quick, put a sliding canopy over that!"
 
eman1200 said:
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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It's because of all the great carrier based planes they built...
 
20171015_101409-459x816-jpg.57132
 
I am thinking about converting the Grumman to a fish tank.
It's so full of water all the time. I should have listened.
 
SixPapaCharlie said:
I feel like I am being setup...
Will it really react?
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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
 
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.
 
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