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Excessive noise on VHF radio when Transmitting

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hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Tue Jun 14, 2016 1:40 pm Post subject: Excessive noise on VHF radio when Transmitting

Gentlemen,

  

 I have a noise problem on the VHF radio system in my plane when I attempt  to transmit. In fact The other day while flying through Class C airspace the  approach controller was telling me that my transmission was broken and had so  much noise he could hardly understand what I was saying. I also hear the noise  in my headphones when I transmit, not when receiving.

  

 I have visually checked all the ground connections on the plane and they  are clear of corrosion and are tight. While on the ground with the engine not  running the radio transmission is fine with no problems. The problem only occurs  when the engine is running. The noise sounds like the frequency of the rotating  generator on the back of the engine which is a Rotax 912 UL. The audible  frequency can be heard to vary with the engine rpm. It is “dirty” noise. My  radio is a panel mounted  ICOM IC-A200. I also have two 10,000 mF  capacitors connected in parallel between the voltage regulator and ground as  noise filters. I have visually checked the two capacitors, and they seem to be  in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI  121 using a quarter wave ground plane. I have had no problems with  this system for ten years.

  

 Here are the specifics:

 Aircraft    Allegro 2000 LSA

 Engine    Rotax 912 UL

 TSN        741 hrs

 Radio     ICOM IC-A200

 Antenna    Comant VHF CI 121

  

 Any and all advice as to how to identify what is causing the problem and  how to correct it would be appreciated.

  

 Hugh G.  McKay III, P.E.

N661WW

email  hgmckay(at)bellsouth.net

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peteohms

Joined: 31 Oct 2007
Posts: 224
Location: Leander, TX

Posted: Tue Jun 14, 2016 2:14 pm Post subject: Excessive noise on VHF radio when Transmitting

Do you have a cigarette lighter USB adapter plugged in? They can cause this.

Pete



On Jun 14, 2016, at 4:39 PM, Hugh McKay <hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)> wrote:

 	  Quote: 	
		      Gentlemen,

  

 I have a noise problem on the VHF radio system in my plane when I attempt  to transmit. In fact The other day while flying through Class C airspace the  approach controller was telling me that my transmission was broken and had so  much noise he could hardly understand what I was saying. I also hear the noise  in my headphones when I transmit, not when receiving.

  

 I have visually checked all the ground connections on the plane and they  are clear of corrosion and are tight. While on the ground with the engine not  running the radio transmission is fine with no problems. The problem only occurs  when the engine is running. The noise sounds like the frequency of the rotating  generator on the back of the engine which is a Rotax 912 UL. The audible  frequency can be heard to vary with the engine rpm. It is “dirty” noise. My  radio is a panel mounted  ICOM IC-A200. I also have two 10,000 mF  capacitors connected in parallel between the voltage regulator and ground as  noise filters. I have visually checked the two capacitors, and they seem to be  in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI  121 using a quarter wave ground plane. I have had no problems with  this system for ten years.

  

 Here are the specifics:

 Aircraft    Allegro 2000 LSA

 Engine    Rotax 912 UL

 TSN        741 hrs

 Radio     ICOM IC-A200

 Antenna    Comant VHF CI 121

  

 Any and all advice as to how to identify what is causing the problem and  how to correct it would be appreciated.

  

 Hugh G.  McKay III, P.E.

N661WW

email  hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)



 

<Hugh.vcf>

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_________________
Pete
Leander, TX
Kitfox III, 912ul, Grove

rlborger(at)mac.com
Guest

Posted: Tue Jun 14, 2016 3:00 pm Post subject: Excessive noise on VHF radio when Transmitting

Hugh,

Do you perchance have an ANR headset?



With my Lightspeed Zulu 2, if the ANR isn’t operating, my transmissions are hopelessly garbled and noisy.  First sign that the batteries in the ANR unit are dying is when the tower can’t understand my transmission due to the engine noise in the cockpit.  



Another source of noise I’ve run into is with some plug=in USB power sources.  Some seem OK others generate a lot of electrical noise.



Blue skies & tailwinds,Bob BorgerEuropa XS Tri, Rotax 914, Airmaster C/S Prop (75 hrs).Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP3705 Lynchburg Dr.Corinth, TX  76208-5331Cel: 817-992-1117rlborger(at)mac.com (rlborger(at)mac.com)



On Jun 14, 2016, at 4:39 PM, Hugh McKay <hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)> wrote:

    Gentlemen,

  

 I have a noise problem on the VHF radio system in my plane when I attempt  to transmit. In fact The other day while flying through Class C airspace the  approach controller was telling me that my transmission was broken and had so  much noise he could hardly understand what I was saying. I also hear the noise  in my headphones when I transmit, not when receiving.

  

 I have visually checked all the ground connections on the plane and they  are clear of corrosion and are tight. While on the ground with the engine not  running the radio transmission is fine with no problems. The problem only occurs  when the engine is running. The noise sounds like the frequency of the rotating  generator on the back of the engine which is a Rotax 912 UL. The audible  frequency can be heard to vary with the engine rpm. It is “dirty” noise. My  radio is a panel mounted  ICOM IC-A200. I also have two 10,000 mF  capacitors connected in parallel between the voltage regulator and ground as  noise filters. I have visually checked the two capacitors, and they seem to be  in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI  121 using a quarter wave ground plane. I have had no problems with  this system for ten years.

  

 Here are the specifics:

 Aircraft    Allegro 2000 LSA

 Engine    Rotax 912 UL

 TSN        741 hrs

 Radio     ICOM IC-A200

 Antenna    Comant VHF CI 121

  

 Any and all advice as to how to identify what is causing the problem and  how to correct it would be appreciated.

  

 Hugh G.  McKay III, P.E.N661WWemail  hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)



 <Hugh.vcf>

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hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Tue Jun 14, 2016 3:13 pm Post subject: Excessive noise on VHF radio when Transmitting

Pete,

  

 My GPS unit is powered for a cigarette lighter plug, but I have been doing  this for ten years w/o a problem.

  

 Hugh G.  McKay III, P.E. Fellow, L.M. ASCE

Senior Consultant

Worldwide Engineering  Inc.

4090 North NC Hwy. 16

Denver, NC 28037



Ph. 704-661-8271

Fax  704-483-5466

email hgmckay(at)bellsouth.net

http://www.wwegeo.com

    

  From: Pete Christensen (pchristensen10(at)austin.rr.com) 

 Sent: Tuesday, June 14, 2016 6:13 PM

 To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)  

 Subject: Re: Excessive noise on VHF radio when  Transmitting

  



  

 Do you have a cigarette lighter USB adapter plugged in? They can cause  this.

  

 Pete

 

On Jun 14, 2016, at 4:39 PM, Hugh McKay <hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)>  wrote:

  	  Quote: 	
		              Gentlemen,

    

   I have a noise problem on the VHF radio system in my plane when I attempt    to transmit. In fact The other day while flying through Class C airspace the    approach controller was telling me that my transmission was broken and had so    much noise he could hardly understand what I was saying. I also hear the noise    in my headphones when I transmit, not when receiving.

    

   I have visually checked all the ground connections on the plane and they    are clear of corrosion and are tight. While on the ground with the engine not    running the radio transmission is fine with no problems. The problem only    occurs when the engine is running. The noise sounds like the frequency of the    rotating generator on the back of the engine which is a Rotax 912 UL. The    audible frequency can be heard to vary with the engine rpm. It is “dirty”    noise. My radio is a panel mounted  ICOM IC-A200. I also have two 10,000    mF capacitors connected in parallel between the voltage regulator and ground    as noise filters. I have visually checked the two capacitors, and they seem to    be in good order (i.e. no swelling or distortion). The antenna is a Comant VHF    CI 121 using a quarter wave ground plane. I have had no problems    with this system for ten years.

    

   Here are the specifics:

   Aircraft    Allegro 2000 LSA

   Engine    Rotax 912 UL

   TSN        741 hrs

   Radio     ICOM IC-A200

   Antenna    Comant VHF CI 121

    

   Any and all advice as to how to identify what is causing the problem and    how to correct it would be appreciated.

    

   Hugh G.    McKay III, P.E.

N661WW

email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)





   <Hugh.vcf>

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hgmckay

Joined: 23 May 2006
Posts: 397

Posted: Tue Jun 14, 2016 3:16 pm Post subject: Excessive noise on VHF radio when Transmitting

Robert,

  

 My head sets are not ANR headsets. My GPS is powered from a cigarette  lighter plug, but it is not a USB.

  

 Hugh G.  McKay III, P.E. Fellow, L.M. ASCE

Senior Consultant

Worldwide Engineering  Inc.

4090 North NC Hwy. 16

Denver, NC 28037



Ph. 704-661-8271

Fax  704-483-5466

email hgmckay(at)bellsouth.net

http://www.wwegeo.com

    

  From: Robert Borger (rlborger(at)mac.com) 

 Sent: Tuesday, June 14, 2016 6:59 PM

 To: rotaxengines-list(at)matronics.com (rotaxengines-list(at)matronics.com)  

 Subject: Re: Excessive noise on VHF radio when  Transmitting

  



 Hugh,    

 Do you perchance have an ANR headset?

  

 With my Lightspeed Zulu 2, if the ANR isn’t operating, my transmissions  are hopelessly garbled and noisy.  First sign that the batteries in the ANR  unit are dying is when the tower can’t understand my transmission due to the  engine noise in the cockpit.  

  

 Another source of noise I’ve run into is with some plug=in USB power  sources.  Some seem OK others generate a lot of electrical noise.

  

 Blue skies & tailwinds,Bob  BorgerEuropa XS Tri, Rotax 914, Airmaster C/S Prop (75  hrs).Little Toot Sport Biplane, Lycoming Thunderbolt  AEIO-320 EXP3705 Lynchburg Dr.Corinth,  TX  76208-5331Cel: 817-992-1117rlborger(at)mac.com (rlborger(at)mac.com)

  

   On Jun 14, 2016, at 4:39 PM, Hugh McKay <hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)> wrote:

  

     Gentlemen,

  

 I have a noise problem on the VHF radio system in my plane when I attempt  to transmit. In fact The other day while flying through Class C airspace the  approach controller was telling me that my transmission was broken and had so  much noise he could hardly understand what I was saying. I also hear the noise  in my headphones when I transmit, not when receiving.

  

 I have visually checked all the ground connections on the plane and they  are clear of corrosion and are tight. While on the ground with the engine not  running the radio transmission is fine with no problems. The problem only occurs  when the engine is running. The noise sounds like the frequency of the rotating  generator on the back of the engine which is a Rotax 912 UL. The audible  frequency can be heard to vary with the engine rpm. It is “dirty” noise. My  radio is a panel mounted  ICOM IC-A200. I also have two 10,000 mF  capacitors connected in parallel between the voltage regulator and ground as  noise filters. I have visually checked the two capacitors, and they seem to be  in good order (i.e. no swelling or distortion). The antenna is a Comant VHF CI  121 using a quarter wave ground plane. I have had no problems with  this system for ten years.

  

 Here are the specifics:

 Aircraft    Allegro 2000 LSA

 Engine    Rotax 912 UL

 TSN        741 hrs

 Radio     ICOM IC-A200

 Antenna    Comant VHF CI 121

  

 Any and all advice as to how to identify what is causing the problem and  how to correct it would be appreciated.

  

 Hugh G. McKay III,  P.E.

N661WW

email hgmckay(at)bellsouth.net (hgmckay(at)bellsouth.net)





<Hugh.vcf>

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Don Maxwell

Joined: 04 Sep 2014
Posts: 4

Posted: Thu Jun 16, 2016 5:43 am Post subject: Excessive noise on VHF radio when Transmitting

That's what I think, too.       I have a Zulu 2 and an original Zulu. The ANR is good enough that       when the batteries die the noise level in my ears is really       disconcerting.  But no one has ever complained about the quality       of my transmissions.  It's possible that they hear more of the       engine noise--I don't know about that--but it couldn't be any       louder than when I used to wear passive headsets in the same       airplane.

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lcfitt3(at)gmail.com
Guest

Posted: Thu Jun 16, 2016 7:04 am Post subject: Excessive noise on VHF radio when Transmitting

I have been watching this thread and hesitated joining in as my experience is minimal, but recently I had periods of severe noise in the headsets.  I don't know if it was in the transmission as my flying is all non towered.  What I found was when charging my tablet through a USB running from a plug in adapter, the adapter had inadequate noise suppression circuitry designed into the dc/dc converter.  I also found that the noise interference was a broadcast RF noise rather than being sent through the wiring.

 Lowell Fitt On Jun 16, 2016 6:47 AM, "Don Maxwell" <DonMaxwell(at)abstractconcreteworks.com (DonMaxwell(at)abstractconcreteworks.com)> wrote: 	  Quote: 	
		                      That's what I think, too.       I have a Zulu 2 and an original Zulu. The ANR is good enough that       when the batteries die the noise level in my ears is really       disconcerting.  But no one has ever complained about the quality       of my transmissions.  It's possible that they hear more of the       engine noise--I don't know about that--but it couldn't be any       louder than when I used to wear passive headsets in the same       airplane.

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