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VHF Transmitting Noise

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bgarlick(at)ford.com
Guest

Posted: Tue Jan 15, 2008 12:41 am Post subject: VHF Transmitting Noise

Hi   

I'd appreciate some comments or advice from avionics installers who half-understand what they're doing? (My limits are that I need to follow manufacturers' installation instructions and wiring diagrams to the letter; and if something doesn't quite work I'm at a complete loss!...Although if any advice was something like connecting a xxx ohm resistor in parallel in a particular circuit, I could manage to cope with that).  

I have just installed an ICOM IC-A200 transceiver coupled with a PS Engineering PM501 Intercom in a newly built Vans RV7, and when I press the PTT switch I get a lot of noise feeding-back into the earphones as I'm talking… The Air Traffic Controllers say they're reading me "fives", and the noise doesn't occur when Receiving or when using the voice-activated intercom.  The noise isn't in time with the engine, but is constant whilst transmitting and sounds like wind blowing across the microphone.  

Any ideas about what could be wrong?     

Thanks   

BillG      [quote][b]

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Jan 15, 2008 8:08 am Post subject: VHF Transmitting Noise

What you have described sounds a lot like alternator whine coming into your audio panel.  If it is, you should be able to remove it by installing a choke in the power line to your PN501.  A choke is simply a coil and a capacitor, in parallel, tuned to remove alternator frequency sound.  It is wired in series in the B+ line of your audio panel and it stops the noise which is coming in on that wire.  Where to get the choke depends on the registration of your plane GA will have to get it from an avionics shop, others, from an electronics or amateur radio outlet.   A lot of AB owners can get a lot of free help from local amateur radio ops.  They really  know what they are doing  form a practical point.  

   

Also check the wires between your transceiver and audio panel have the shield grounded only at one end.  

   

The last piece of advice is the one that is a pain...  When you get  your system working draw up a little block interconnect diagram of exactly what you have there so if you have future problems you will have an idea where to look. You can start on that interconnect diagram ASAP even before installing a choke.  Better avionics shops won’t put a finger on an installation until they have finished their interconnect diagram.  Doing that makes for less mistakes in installation and much less problems.  Things to include in the interconnect diagram are wire connecters and fuse locations.  

   

Hope this helps   

   

Noel  

       

From: owner-avionics-list-server(at)matronics.com [mailto:owner-avionics-list-server(at)matronics.com] On Behalf Of Garlick, Bill (W.D.)

 Sent: Tuesday, January 15, 2008 5:10 AM

 To: avionics-list(at)matronics.com

 Subject: VHF Transmitting Noise  

  

  

   

Hi   

I'd appreciate some comments or advice from avionics installers who half-understand what they're doing? (My limits are that I need to follow manufacturers' installation instructions and wiring diagrams to the letter; and if something doesn't quite work I'm at a complete loss!...Although if any advice was something like connecting a xxx ohm resistor in parallel in a particular circuit, I could manage to cope with that).  

I have just installed an ICOM IC-A200 transceiver coupled with a PS Engineering PM501 Intercom in a newly built Vans RV7, and when I press the PTT switch I get a lot of noise feeding-back into the earphones as I'm talking… The Air Traffic Controllers say they're reading me "fives", and the noise doesn't occur when Receiving or when using the voice-activated intercom.  The noise isn't in time with the engine, but is constant whilst transmitting and sounds like wind blowing across the microphone.  

Any ideas about what could be wrong?     

Thanks   

BillG     	  Quote: 	
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_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

donmorrisey

Joined: 17 Mar 2007
Posts: 18

Posted: Wed Jan 16, 2008 7:06 am Post subject: VHF Transmitting Noise

Hi Bill, you may want to look into this product: http://miracleantenna.com/smoothie.htm

  

 I have no personal experience with it, but it was mentioned on the yahoo jabiru engine list in regard to engine noise.  It does have the capacitor Noel mentions.

  

 If you do use it I would be curious to know your results.

  

 Don...



www.donsbushcaddy.com

Don Morrisey's Skunkworks



  	  Quote: 	
		    Subject: VHF Transmitting Noise

Date: Tue, 15 Jan 2008 08:40:04 +0000

From: bgarlick(at)ford.com

To: avionics-list(at)matronics.com



  

Hi  

I'd appreciate some comments or advice from avionics installers who half-understand what they're doing? (My limits are that I need to follow manufacturers' installation instructions and wiring diagrams to the letter; and if something doesn't quite work I'm at a complete loss!...Although if any advice was something like connecting a xxx ohm resistor in parallel in a particular circuit, I could manage to cope with that). 

I have just installed an ICOM IC-A200 transceiver coupled with a PS Engineering PM501 Intercom in a newly built Vans RV7, and when I press the PTT switch I get a lot of noise feeding-back into the earphones as I'm talking… The Air Traffic Controllers say they're reading me "fives", and the noise doesn't occur when Receiving or when using the voice-activated intercom.  The noise isn't in time with the engine, but is constant whilst transmitting and sounds like wind blowing across the microphone. 

Any ideas about what could be wrong?    

Thanks  

BillG   	  Quote: 	
		  



 target=_blank>http://www.matronics.com/Navigator?Avionics-List

p://forums.matronics.com

blank>http://www.matronics.com/contribution



	
	
Get the power of Windows + Web with the new Windows Live. Get it now!  [quote][b]

_________________
Don...
BushCaddy R120
http://www.donsbushcaddy.com

bgarlick(at)ford.com
Guest

Posted: Wed Jan 16, 2008 7:31 am Post subject: VHF Transmitting Noise

Thanks Don, I was able access the website (after inserting www) and immediately spotted the choke that Noel suggested sitting in the middle of the circuit board picture.  I might give it a try and will let you know how it works…it's worth the relatively high cost if it gets rid of that damn noise!  (…I've found out already I can get a Toroid choke from a local electronics store for GBP2.26 = USD4.63)  

BillG – RV7  

   

        

  

From: owner-avionics-list-server(at)matronics.com [mailto:owner-avionics-list-server(at)matronics.com] On Behalf Of Don Morrisey

 Sent: Wednesday, January 16, 2008 3:04 PM

 To: avionics-list(at)matronics.com

 Subject: RE: VHF Transmitting Noise  

  

   

Hi Bill, you may want to look into this product: http://miracleantenna.com/smoothie.htm

  

 I have no personal experience with it, but it was mentioned on the yahoo jabiru engine list in regard to engine noise.  It does have the capacitor Noel mentions.

  

 If you do use it I would be curious to know your results.

  

 Don...

 

 www.donsbushcaddy.com

 Don Morrisey's Skunkworks

 

 

       

  

Subject: VHF Transmitting Noise

 Date: Tue, 15 Jan 2008 08:40:04 +0000

 From: bgarlick(at)ford.com

 To: avionics-list(at)matronics.com  

Hi   

I'd appreciate some comments or advice from avionics installers who half-understand what they're doing? (My limits are that I need to follow manufacturers' installation instructions and wiring diagrams to the letter; and if something doesn't quite work I'm at a complete loss!...Although if any advice was something like connecting a xxx ohm resistor in parallel in a particular circuit, I could manage to cope with that).  

I have just installed an ICOM IC-A200 transceiver coupled with a PS Engineering PM501 Intercom in a newly built Vans RV7, and when I press the PTT switch I get a lot of noise feeding-back into the earphones as I'm talking… The Air Traffic Controllers say they're reading me "fives", and the noise doesn't occur when Receiving or when using the voice-activated intercom.  The noise isn't in time with the engine, but is constant whilst transmitting and sounds like wind blowing across the microphone.  

Any ideas about what could be wrong?     

Thanks   

BillG     	  Quote: 	
		     target=_blank>http://www.matronics.com/Navigator?Avionics-Listp://forums.matronics.comblank>http://www.matronics.com/contribution 	
  

       

  

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      [quote][b]

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 16, 2008 1:34 pm Post subject: VHF Transmitting Noise

I went to check the site but got a 404 error then I tried to get to the root directory and got a password block.  

   

The unit, a choke, is a coil with a capacitor usually in the centre of the coil. It is wired in series with the power line.  A capacitor can be used to filter a different kind of noise if it is just connected between the power line and the ground....  Capacitors don’t conduct DC current.  A capacitor set up the second way is generally used to smooth out DC voltage in power supplies.  

   

Noel  

       

From: owner-avionics-list-server(at)matronics.com [mailto:owner-avionics-list-server(at)matronics.com] On Behalf Of Don Morrisey

 Sent: Wednesday, January 16, 2008 11:34 AM

 To: avionics-list(at)matronics.com

 Subject: RE: VHF Transmitting Noise  

  

  

   

Hi Bill, you may want to look into this product: http://miracleantenna.com/smoothie.htm

  

 I have no personal experience with it, but it was mentioned on the yahoo jabiru engine list in regard to engine noise.  It does have the capacitor Noel mentions.

  

 If you do use it I would be curious to know your results.

  

 Don...

 

 www.donsbushcaddy.com

 Don Morrisey's Skunkworks

 

 

       

  

Subject: VHF Transmitting Noise

 Date: Tue, 15 Jan 2008 08:40:04 +0000

 From: bgarlick(at)ford.com

 To: avionics-list(at)matronics.com  

Hi   

I'd appreciate some comments or advice from avionics installers who half-understand what they're doing? (My limits are that I need to follow manufacturers' installation instructions and wiring diagrams to the letter; and if something doesn't quite work I'm at a complete loss!...Although if any advice was something like connecting a xxx ohm resistor in parallel in a particular circuit, I could manage to cope with that).  

I have just installed an ICOM IC-A200 transceiver coupled with a PS Engineering PM501 Intercom in a newly built Vans RV7, and when I press the PTT switch I get a lot of noise feeding-back into the earphones as I'm talking… The Air Traffic Controllers say they're reading me "fives", and the noise doesn't occur when Receiving or when using the voice-activated intercom.  The noise isn't in time with the engine, but is constant whilst transmitting and sounds like wind blowing across the microphone.  

Any ideas about what could be wrong?     

Thanks   

BillG     	  Quote: 	
		     target=_blank>http://www.matronics.com/Navigator?Avionics-Listp://forums.matronics.comblank>http://www.matronics.com/contribution 	
  

       

  

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       [quote][b]

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Jan 16, 2008 1:48 pm Post subject: VHF Transmitting Noise

Thanks for the key to get into the site.  That unit appears to be an excellent choice.   It will choke out a number of different frequencies, I’m sure, and it will help with voltage fluctuations.  

   

A good choice It looks heavy enough to install across the feed to your avionics buss if your plane is wired that way.  

   

Noel  

       

From: owner-avionics-list-server(at)matronics.com [mailto:owner-avionics-list-server(at)matronics.com] On Behalf Of Garlick, Bill (W.D.)

 Sent: Wednesday, January 16, 2008 11:58 AM

 To: avionics-list(at)matronics.com

 Subject: RE: VHF Transmitting Noise  

  

  

     

Thanks Don, I was able access the website (after inserting www) and immediately spotted the choke that Noel suggested sitting in the middle of the circuit board picture.  I might give it a try and will let you know how it works…it's worth the relatively high cost if it gets rid of that damn noise!  (…I've found out already I can get a Toroid choke from a local electronics store for GBP2.26 = USD4.63)  

BillG – RV7  

   

        

  

From: owner-avionics-list-server(at)matronics.com [mailto:owner-avionics-list-server(at)matronics.com] On Behalf Of Don Morrisey

 Sent: Wednesday, January 16, 2008 3:04 PM

 To: avionics-list(at)matronics.com

 Subject: RE: VHF Transmitting Noise  

  

   

Hi Bill, you may want to look into this product: http://miracleantenna.com/smoothie.htm

  

 I have no personal experience with it, but it was mentioned on the yahoo jabiru engine list in regard to engine noise.  It does have the capacitor Noel mentions.

  

 If you do use it I would be curious to know your results.

  

 Don...

 

 www.donsbushcaddy.com

 Don Morrisey's Skunkworks

 

       

  

Subject: VHF Transmitting Noise

 Date: Tue, 15 Jan 2008 08:40:04 +0000

 From: bgarlick(at)ford.com

 To: avionics-list(at)matronics.com  

Hi   

I'd appreciate some comments or advice from avionics installers who half-understand what they're doing? (My limits are that I need to follow manufacturers' installation instructions and wiring diagrams to the letter; and if something doesn't quite work I'm at a complete loss!...Although if any advice was something like connecting a xxx ohm resistor in parallel in a particular circuit, I could manage to cope with that).  

I have just installed an ICOM IC-A200 transceiver coupled with a PS Engineering PM501 Intercom in a newly built Vans RV7, and when I press the PTT switch I get a lot of noise feeding-back into the earphones as I'm talking… The Air Traffic Controllers say they're reading me "fives", and the noise doesn't occur when Receiving or when using the voice-activated intercom.  The noise isn't in time with the engine, but is constant whilst transmitting and sounds like wind blowing across the microphone.  

Any ideas about what could be wrong?     

Thanks   

BillG     	  Quote: 	
		     target=_blank>http://www.matronics.com/Navigator?Avionics-Listp://forums.matronics.comblank>http://www.matronics.com/contribution 	
  

       

  

Get the power of Windows + Web with the new Windows Live. Get it now!    	  Quote: 	
		    http://www.matronics.com/contribution  	
0 	  Quote: 	
		   	
1 	  Quote: 	
		   	
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       [quote][b]

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

donmorrisey

Joined: 17 Mar 2007
Posts: 18

Posted: Wed Jan 16, 2008 2:05 pm Post subject: VHF Transmitting Noise

Hi Noel, I had the link wrong.

  

 Here is the correct link: http://www.miracleantenna.com/smoothie/htm

  

 Don



www.donsbushcaddy.com

Don Morrisey's Skunkworks



  	  Quote: 	
		    From: noelloveys(at)yahoo.ca

To: avionics-list(at)matronics.com

Subject: RE: VHF Transmitting Noise

Date: Wed, 16 Jan 2008 17:56:35 -0330



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I went to check the site but got a 404 error then I tried to get to the root directory and got a password block. 

  

The unit, a choke, is a coil with a capacitor usually in the centre of the coil. It is wired in series with the power line.  A capacitor can be used to filter a different kind of noise if it is just connected between the power line and the ground....  Capacitors don’t conduct DC current.  A capacitor set up the second way is generally used to smooth out DC voltage in power supplies. 

  

Noel 

 

	
Share life as it happens with the new Windows Live. Start sharing!  [quote][b]

_________________
Don...
BushCaddy R120
http://www.donsbushcaddy.com

jetboy

Joined: 22 Jul 2006
Posts: 233

Posted: Thu Jan 17, 2008 11:37 pm Post subject: Re: VHF Transmitting Noise

Bill,

      Another thing to check is that the sidetone produced by the IC 200 is not adding to any sidetone provided by the PS intercom.



There might be instructions about this on the PS engineering site.



 The IC 200 can be withdrawn from its tray, on the top cover there will be an adjustment hole marked "S-tone" which you can reset all the way back or fwd as the case may be, to prevent the radio putting a sample of your voice into the earphones during transmission. I expect the intercom already does this for you, so you dont require it twice. 



Ralph

_________________
Ralph - CH701 / 2200a

bgarlick(at)ford.com
Guest

Posted: Fri Jan 18, 2008 12:59 am Post subject: VHF Transmitting Noise

Ralph,

Thanks for your suggestion, I'll certainly try that...it's worth

investigating as the noise seems to be in time with my transmissions

rather than a regular mechanical interference.  I remember seeing the

S-tone adjustment hole during installation but I didn't pay too much

attention to it at the time. (My biggest concern then was would the

radio and intercom actually work after my wiring efforts)



Regards

Bill



--

Lennart

Joined: 06 Jun 2008
Posts: 1
Location: Tullinge, Sweden

Posted: Fri Jun 06, 2008 6:09 am Post subject: Re: VHF Transmitting Noise

Hi BillG,

is the noise gone? I have the same issue and the same radio and is curious about the result.



Rgds

Lennart

RV-7A

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