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Radio transmission problem

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trigo(at)mail.telepac.pt
Guest

Posted: Thu Aug 25, 2016 3:55 am Post subject: Radio transmission problem

Bob and all



A friend of mine has a Cessna 182 Skylane, and in the last flights ATC people complained that his transmissions were barely readable.



Trying to find out the problem, I tested with a small simple Tx tester, and it seems to be 5x5.



Then I tried with a handheld on the ground, some 300 ft away from the airplane, and it received very well.



What should I test further?



After those tests, I also noticed that the electric altimeter is getting interference (needle moves) when I press the PTT.



Further, since I don't find any nut there, can somebody explain how to uninstall the yoke mounted PTT switch?



Thanks

Carlos

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user9253

Joined: 28 Mar 2008
Posts: 1924
Location: Riley TWP Michigan

Posted: Thu Aug 25, 2016 4:29 am Post subject: Re: Radio transmission problem

Check the radio antenna ground and check both ends of the coax for tightness and for corrosion.

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_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Aug 25, 2016 9:03 am Post subject: Radio transmission problem

At 06:53 AM 8/25/2016, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: Carlos Trigo <trigo(at)mail.telepac.pt>



 Bob and all



 A friend of mine has a Cessna 182 Skylane, and in the last flights ATC people complained that his transmissions were barely readable.



 Trying to find out the problem, I tested with a small simple Tx tester, and it seems to be 5x5.



 Then I tried with a handheld on the ground, some 300 ft away from the airplane, and it received very well.



 What should I test further?



 After those tests, I also noticed that the electric altimeter is getting interference (needle moves) when I press the PTT. 	


   Check SWR on the antenna feedline AT THE RADIO.



   It sounds like you've got a coax shield open at

   one end. The hand-held from 300 feet way would

   hear the ship's radio if then antenna were a

   wet string. But your observation of heretofore

   non-existent interference to panel mounted goodies

   strongly suggests the cockpit is being flooded

   with RF that is not being constrained INSIDE the

   feedline.



 

 

   Bob . . .

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