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radio noise

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gcomfo(at)tc3net.com
Guest

Posted: Sun Mar 17, 2013 10:24 am Post subject: radio noise

Bob, et  al:

 Been a long time  since I posted to any list but this time I have a question.  My RV-4 com  radio when neither transmitting nor receiving presents noise to the headsets  that is unacceptable.  An incoming signal of reasonable strength comes  through clearly and the transmit has been ok, but one pilot described my signal  as weak.  The radio is a Walter Dittel FSG71 and has been checked by  Peninsula Avionics and found to be ok, or at least not found to be  defective.  The tech type that worked on it suggested checking the  antenna for good base contact with the metal skin. I removed the antenna  thinking that there might be corrosion (20 years in service) and found the  faying surfaces to be coated with oil but with bright metal on both sides.   I have been through all the connections and find no anomalies.  Headset  jacks are insulated with clean contacts.  The Sigtronics intercom is wired  through the radio and when the radio is turned off, works  fine.

  

 Questions:   Would the presense of oil compromise the antenna performance and if so, would  dielectric grease serve to improve it?

                     Is there a failure mode for the antenna itself that could result in the above  symptoms and how could one tell?

  

 Thank you very  much.

 We should talk some  time.

  

 Gordon  Comfort

 N363GC

    [quote][b]

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gcomfo(at)tc3net.com
Guest

Posted: Sun Mar 17, 2013 11:33 am Post subject: radio noise

Bob, et  al:

 Been a long time  since I posted to any list but this time I have a question.  My RV-4 com  radio when neither transmitting nor receiving presents noise to the headsets  that is unacceptable.  An incoming signal of reasonable strength comes  through clearly and the transmit has been ok, but one pilot described my signal  as weak.  The radio is a Walter Dittel FSG71 and has been checked by  Peninsula Avionics and found to be ok, or at least not found to be  defective.  The tech type that worked on it suggested checking the  antenna for good base contact with the metal skin. I removed the antenna  thinking that there might be corrosion (20 years in service) and found the  faying surfaces to be coated with oil but with bright metal on both sides.   I have been through all the connections and find no anomalies.  Headset  jacks are insulated with clean contacts.  The Sigtronics intercom is wired  through the radio and when the radio is turned off, works  fine.

  

 Questions:   Would the presense of oil compromise the antenna performance and if so, would  dielectric grease serve to improve it?

                     Is there a failure mode for the antenna itself that could result in the above  symptoms and how could one tell?

  

 Thank you very  much.

 We should talk some  time.

  

 Gordon  Comfort

 N363GC



    [quote][b]

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Mar 17, 2013 12:57 pm Post subject: radio noise

 	  Quote: 	
		  At 01:24 PM 3/17/2013, you wrote:


	


 	  Quote: 	
		  Bob, et al:

Been a long time since I posted to any list but this time I have a question.


	


    It HAS been a long time my friend. Hope you and Marge are

    both well . . .



 	  Quote: 	
		     My RV-4 com radio when neither transmitting nor receiving 

 presents noise to the headsets that is unacceptable.  An incoming 

 signal of reasonable strength comes through clearly and the 

 transmit has been ok, but one pilot described my signal as 

 weak.  The radio is a Walter Dittel FSG71 and has been checked by 

 Peninsula Avionics and found to be ok, or at least not found to be 

 defective.  The tech type that worked on it suggested checking the 

 antenna for good base contact with the metal skin. I removed the 

 antenna thinking that there might be corrosion (20 years in 

 service) and found the faying surfaces to be coated with oil but 

 with bright metal on both sides.  I have been through all the 

 connections and find no anomalies.  Headset jacks are insulated 

 with clean contacts.  The Sigtronics intercom is wired through the 

 radio and when the radio is turned off, works fine.



Questions:  Would the presense of oil compromise the antenna 

performance and if so, would dielectric grease serve to improve it?


	


    Probably not if the screws were tight.



 	  Quote: 	
		  Is there a failure mode for the antenna itself that could result in 

the above symptoms and how could one tell?


	


    Probably not for the antenna but certainly for the coax.

    Connectors on both ends are solidly attached? Do you have

    access to an SWR meter?



    Do I interpret your words to mean that only one pilot

    has complained about your signals being 'weak'?



    Listener interpretation of signal quality is an iffy

    sort of thing. Somebody with a rich history in radio

    communications, particularly AM would have an 'ear' for

    various quality issues which go to modulation depth,

    distortions, and overall signal strength. In other words

    have a grey bearded ham listen to your signal on a hand

    held from a mile or so away.



    Also, take the first opportunity in a unicom environment

    to ask several other pilots how your signals sound in

    relation to others in the same conversation. The single,

    isolated signal report may not be terribly reliable.



 	  Quote: 	
		  

Thank you very much.

We should talk some time.


	


    Let's do that. I think I've still got your mobile number

    in my phone from our last meeting at OSH . . . I think that

    was 2007. Does your number still end in 6966?

   Bob . . .

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gcomfo(at)tc3net.com
Guest

Posted: Sun Mar 17, 2013 3:40 pm Post subject: radio noise

--

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