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369PL

Joined: 08 Sep 2006
Posts: 20

Posted: Sat Jun 13, 2009 1:21 pm Post subject: radio noise

I was flying my plane last weekend. I noticed I had a lot of radio noise. was flying with two other planes. They said radio transmission was garbled. I started experimenting turning off electronic things one at a time. Found out my GPS was the culprit. A Garmin 195. My radio is a Icom IC-A22. Anyone have any suggestions?

KITFOXZ(at)aol.com
Guest

Posted: Sat Jun 13, 2009 4:54 pm Post subject: radio noise

In a message dated 6/13/2009 5:23:25 P.M. Eastern Daylight Time,  n3pupnc(at)aol.com writes:

  	  Quote: 	
		  I was    flying my plane last weekend. I noticed I had a lot of radio noise. was flying    with two other planes. They said radio transmission was garbled. I started    experimenting turning off electronic things one at a time. Found out my GPS    was the culprit. A Garmin 195. My radio is a Icom IC-A22. Anyone have any    suggestions? 	
  

 Hello 369PL,

  

 I'll give you some ideas on what to take a look at.  I will assume  your avionics package was working well together at some point and now there are  noise problems.  Radio noise or interference comes into your radio from one  of two sources, the antenna or the power supply.

  

 As an avionics tech I know to tell you to always look at the power  supply first.  Get a digital volt meter from Radio Shack or from your local  Lowes or home store.  An expensive one is not necessary.  Measure the  voltage of your battery with the volt meter.  Do this with the meter leads  connected directly across the battery posts first, not the battery terminals  but, the battery posts.  A good reading with a fully charged battery is  12.5 to 13 VDC.  Poor (corroded) battery terminal connections or a weak or  bad battery could very likely be your whole problem. 

  

 Then, read the battery voltage with the engine running and the alternator  online.  Check the reading at several engine RPMs.  You want to see  the voltage remain consistent at about 13.8 to 14.0 VDC.  Now read those  voltages with the negative lead of the meter connected to the ship's ground (a  good bare metal point on the fuselage) and the positive lead connected to the  positive battery post.  Use the engine block for the negative meter lead  point next.  What you are looking for is consistent voltage readings  that will indicate that your ship is well bonded to the negative side of the  battery.

  

 Next read the voltage with the negative meter lead connected to your  avionics common ground point or negative power bus.  Read the voltage  with the positive meter lead connected to the avionics positive power bus and  the negative lead connected to the negative bus point and then check it with the  negative lead connected to the battery negative post and then to the fuselage  bare ground point.  These reading should all be the same.  

  

 Read the voltage from the negative post of the battery to the bare fuselage  ground point and next from the negative post of the battery to the engine  block.  This reading is made with either meter lead connected.  Meter  lead polarity is not a concern here, what you are checking for is to see that no  voltage is measured between the negative post of the battery and any ground  point.  Ground bonding is very important and this reading is proof of it's  integrity. 

  

 Finally, read the voltage with the positive meter lead connected to your  radio's power connection point and the negative lead connected to the battery  negative post and then to ground.  

  

 This reading could have been done first and would tell us a lot but, I just  wanted you to be sure of all of your power system's critical readings  first.  The radio needs to see a solid 12.5 to 13.8 voltage measured across  it's power input to be able to perform well and it needs to be well  grounded.  Take this reading with the radio keyed also and with the engine  running at different RPMs.

  

 Repeat these readings for the GPS receiver too.  It is very likely  that you have a poor ground for the GPS receiver or your radio.

  

 Another approach is to do a blind "TEST AND SEE": Connect a jumper wire  from the negative battery post to the chassis of your radio and next to your  GPS's chassis.  If the noise goes away, you will know the problem is  improper grounding.

  

 If the GPS receiver is not grounded well, it will become a source for radio  interference noise that gets "received" by your radio's antenna input  circuits.  The same grounding problem for the radio can cause the  radio receiver to "see" signals that are not really there because it's improper  grounding makes it detect "ghost" signals.  The radio needs a solid signal  reference ground and a solid power ground to do it's thing well.

  

 This has ended up being a bit long so check these readings out and then I  can suggest some other things to look at.  You could just simply have a bad  GPS receiver too!

  

 John

  

 John P. Marzluf

 Columbus, OHio

 Outback (out back in the garage)    

  

  

  

    

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thesupe(at)hotmail.com
Guest

Posted: Sat Jun 13, 2009 8:13 pm Post subject: radio noise

A while back I rearanged things on the panel and had the GPS next to my handheld radio.  I noticed noise on the radio also which quit if I shut the GPS off.  Ended up moving the handheld over to my left which put them about 2' apart and the noise went away.  Might be worth a try to get some distance between them.  Take care C  Jim Chuk  Avids C Kitfox.  Mn

 

 	  Quote: 	
		   Subject: Kitfox-List: radio noise

 From: n3pupnc(at)aol.com

 Date: Sat C 13 Jun 2009 14:21:51 -0700

 To: kitfox-list(at)matronics.com

 

 --> Kitfox-List message posted by: "369PL" <n3pupnc(at)aol.com>

 

 I was flying my plane last weekend. I noticed I had a lot of radio noise. was flying with two other planes. They said radio transmission was garbled. I started experimenting turning off electronic things one at a time. Found out my GPS was the culprit. A Garmin 195. My radio is a Icom IC-A22. Anyone have any suggestions?

 

 

 

 

 Read this topic online here:

 

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Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Sat Jun 13, 2009 10:35 pm Post subject: radio noise

 	  Quote: 	
		   From: 369PL [n3pupnc(at)aol.com]

 Found out my GPS was the culprit. A Garmin 195. My radio is a Icom IC-A22. 


	


And this is why we are asked to switch off all electronic instruments as we board an airliner. The GPS is only a receiver and shouldn't produce any radio frequency interferences. But any receiver with a malfunction can work as a sender.

By the way, I was wondering: Does your GPS have a Bluetooth port? Perhaps that's the problem. If so, can you disable it?



Cheers,

Michel Verheughe

Norway

Kitfox 3 - Jabiru 2200



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dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Jun 14, 2009 1:56 am Post subject: Re: radio noise

I have a Garmin 196 on left side of dash and Icom handheld on right side.  I only get RF issues when tuned around 119 area .  I have to run the squelch at max .  



I have no transmit or receive issues.  You will always get some RF leakage from a GPS as they have a micro processor inside.  



I see guys with troubles, poor wiring, bad grounds, poor connectors and cheap coax. That is 95 % of radio issues right there.

Dave

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Guest

Posted: Sun Jun 14, 2009 5:49 am Post subject: radio noise

A few years ago on the Aeroelectric list there was a discussion as to 

how far the GPS antenna should be from the radio antenna. My fabulous 

memory indicates that 2' would eliminate any conflict. Of course for 

hand held units is pretty easy to just move them apart. For panel 

mounting hand helds be sure to keep them on separate ends of the 

panel. Not every combination of different units will have conflict. 

Example; in my truck I have a Lowrance powered remote GPS antenna 

about 3" from my VHF antenna and have no conflict at all. I even have 

a Serius antenna within 3" of both and all is well. In my truck 

example the Lowrance head is mounted 2" from the VHF radio. Different 

results for different units.

Paul

======================



At 03:56 AM 6/14/2009, you wrote:

 	  Quote: 	
		  



I have a Garmin 196 on left side of dash and Icom handheld on right 

side.  I only get RF issues when tuned around 119 area .  I have to 

run the squelch at max .



I have no transmit or receive issues.  You will always get some RF 

leakage from a GPS as they have a micro processor inside.



I see guys with troubles, poor wiring, bad grounds, poor connectors 

and cheap coax. That is 95 % of radio issues right there.

Dave



--------

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http://www.cfisher.com/

Awesome *New Forum *

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http://www.youtube.com/profile_videos?user=kitfoxflyer





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 48015#248015

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Jun 14, 2009 9:06 am Post subject: Re: radio noise

Rf will come from processor in GPS . I only get a conflict around the 118 to 120  area. after that no issues.   My antenna is mounted on turtle deck for radio and GPS antenna on dash. 



Dave

Float Flyr

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

Posted: Sun Jun 14, 2009 3:24 pm Post subject: radio noise

GPS units have a microprocessor a possible source of RFI (Radio Frequency

Interference)  They also have LCD screens or TFT screens which can certainly

cause a lot of RFI noise at very close range.  



Most of the airlines ask you to turn off for two reasons...  one is some of

the planes are fly by wire and the other reason is they get a royalty every

time you use their sat phone.  Generally speaking computers which are now ok

are a lot noisier than phones or radio receivers which they also don't want

to see....  the excuse there is that the IF frequency will interfere with

nav and com systems...  they never mention that almost every flight

something minor goes wrong on the flight deck and they don't want you to

start a panic behind them.



Noel



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Kitfox III-A
Aerocet 1100 Floats

MDKitfox(at)aol.com
Guest

Posted: Sun Jun 14, 2009 6:19 pm Post subject: radio noise

On Jun 14, 2009, at 9:53 PM, Noel wrote:

 	  Quote: 	
		  they never mention that almost every flight

something minor goes wrong on the flight deck and they don't want you to

start a panic behind them. 	


Noel,



Everything you said was alright until this point, but really, I flew RJ's (lots of electronics - EFIS, MFD, EICAS, etc.) for years and I had very few flights where anything went wrong.  I'm not sure where you got the stats from, but they seem skewed.  BTW, we didn't have Sat phones so royalties weren't an issue for us, I think you may be right about that one.





Rick Weiss

N39RW Series V Speedster, 912ULS

SkyStar S/N 1

Port Orange, FL

=  [quote][b]

369PL

Joined: 08 Sep 2006
Posts: 20

Posted: Mon Jun 15, 2009 3:26 am Post subject: Re: radio noise

I flew my plane yesterday for a about 30 min. I used batteries in the gps instead of the 12v plane power. I had no noise. I then unhooked the batteries and plugged back into the plane and still no noise. I guess I have a intermitten problem. My gps does not have a bluetooth. I checked the voltage with the gps it says 9.6 my volt meeter says 12.9 the volt meeter on the dash says almost 14. I have noticed that when I run my stobes my engine temp jumps up about 20 degrees (indicated not actual). I have a grey head 582. with a key west rectifier. How much joltage should I have. I will will take my cowl off this week and check the ground connection as suggested.

Thanks guys for the suggestions

Warren

Float Flyr

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

Posted: Mon Jun 15, 2009 5:11 am Post subject: radio noise

That actually came from the days when after every trans-Atlantic flight there would be several jugs on the huge 28 cylinder engines replaced.  They used to say you could tell who the AME at the airport was... he always drove the biggest car! So much overtime replacing jugs.  Years ago there was a guy who used to fly a connie from England to Canada as a freighter.  On one trip in mid Atlantic he lost one engine.  Rather than feathering the blades  and dragging it the rest of the way.  He didn’t think he had the fuel to make it anywhere with his load, he fined the pitch and caused the prop to over rev until for lack of oil the engine seized and tore itself off the plane.  He then landed in Gander and had the engine, mount, cowling etc. replaced.  

   

The other point is what you as a pilot could consider a standard operating procedure, a passenger who is on their first flight, could get worried about.  Even ATC communications can be misinterpreted as a problem and create anxiety in the cabin.  I remember talking to an aircraft maintenance instructor about his first flight in a BAE 146.  When the tucked the gear he thought the side was coming out of the plane... it was worse when the gear was dropped!  All that was normal but if it caused a seasoned maintenance engineer some concern imagine what it would do to some guy who heard on his pocket radio the plane sent for a go around because of wind shear!  

   

When I studied aircraft maintenance we had one young fellow in our class that you couldn’t crowbar into a plane to go for a flight.  He ended up joining the Canadian military and now he has to fly...not only that he has to fly on planes he is responsible for... Looks good on him J  

   

Noel  

       

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of Weiss Richard

 Sent: 14 June 2009 11:49 PM

 To: kitfox-list(at)matronics.com

 Subject: Re: RE: radio noise  

  

  

   

             

   

  

  

  

  

   

  

       

On Jun 14, 2009, at 9:53 PM, Noel wrote:  

  



 

   

they never mention that almost every flight

 something minor goes wrong on the flight deck and they don't want you to

 start a panic behind them.  

    

   

    

Noel,  

  

     

Everything you said was alright until this point, but really, I flew RJ's (lots of electronics - EFIS, MFD, EICAS, etc.) for years and I had very few flights where anything went wrong.  I'm not sure where you got the stats from, but they seem skewed.  BTW, we didn't have Sat phones so royalties weren't an issue for us, I think you may be right about that one.  

    

   

    

   

        

Rick Weiss  

    

N39RW Series V Speedster, 912ULS  

    

SkyStar S/N 1  

    

Port Orange, FL  

  

  

   

  

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Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

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

Posted: Mon Jun 15, 2009 6:22 am Post subject: radio noise

13.8V.



Due to the limited output of the alternator (around 16A or 220 Watts) I'm a

bit surprised about the temperature increase while running your strobes.  If

you turn the strobes off how long does it take for your temperature to come

down again?  Do you experience any loss of rpm?

Noel



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Kitfox III-A
Aerocet 1100 Floats

akflyer

Joined: 07 May 2007
Posts: 574
Location: Soldotna AK

Posted: Mon Jun 15, 2009 8:46 am Post subject: Re: radio noise

sounds more and more like a bad ground to me.  The temp jumping when you hit the strobes is a pretty good indicator, and the noise going away when you unplugged then plugged the GPS back in would suggest a loose connection or possible broken wire.

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369PL

Joined: 08 Sep 2006
Posts: 20

Posted: Mon Jun 15, 2009 5:39 pm Post subject: Re: radio noise

Noel.

The temp drops as soon as you tune the switch off. It raises as soon as you turn it on.It does the same with the position lights and the cabin heater. The rpms stay constant.

Warren

Float Flyr

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

Posted: Mon Jun 15, 2009 7:02 pm Post subject: radio noise

Sounds like a problem with the temp gauge... is it a standard thermocouple?

( unpowered)



Noel



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dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Jun 16, 2009 1:57 am Post subject: Re: radio noise

Warren,  



Different GPS use different voltages. So will regulate voltage themselves.  MY Garmin 196 uses 4  AA batteries   = 6V .  but will take power  10 to 40 V . 



If you getting noise through your power  you got other issues. 



Try moving a handheld  radio near your GPS with both turned out  through differnt freq.  You will find some RFI/ EMI  causes some noise.

DAve



 	  369PL wrote: 	
		  I flew my plane yesterday for a about 30 min. I used batteries in the gps instead of the 12v plane power. I had no noise. I then unhooked the batteries and plugged back into the plane and still no noise. I guess I have a intermitten problem. My gps does not have a bluetooth. I checked the voltage with the gps it says 9.6 my volt meeter says 12.9 the volt meeter on the dash says almost 14. I have noticed that when I run my stobes my engine temp jumps up about 20 degrees (indicated not actual). I have a grey head 582. with a key west rectifier. How much joltage should I have. I will will take my cowl off this week and check the ground connection as suggested.

Thanks guys for the suggestions

Warren

KITFOXZ(at)aol.com
Guest

Posted: Tue Jun 16, 2009 2:52 am Post subject: radio noise

In a message dated 6/15/2009 7:27:58 A.M. Eastern Daylight Time,  n3pupnc(at)aol.com writes:

  	  Quote: 	
		  I flew    my plane yesterday for a about 30 min. I used batteries in the gps instead of    the 12v plane power. I had no noise. I then unhooked the batteries and plugged    back into the plane and still no noise. I guess I have a intermitten problem.    My gps does not have a bluetooth. I checked the voltage with the gps it says    9.6 my volt meeter says 12.9 the volt meeter on the dash says almost 14. I    have noticed that when I run my stobes my engine temp jumps up about 20    degrees (indicated not actual). I have a grey head 582. with a key west    rectifier. How much joltage should I have. I will will take my cowl off this    week and check the ground connection as suggested.

Thanks guys for the    suggestions

Warren 	
  

 Warren,

  

 Some GPS receivers have the capability of reading out their own power  supply voltage.  It sounds like yours has 6 dry cell batteries that will  total a nominal 9 volts, 9.6 volts is a good reading with all batteries up  to snuff.  On external (ship's) power your GPS may be able to accept a wide  range of voltage input, say from 6 to 40 volts.  Check your owner's  manual.

  

 I am thinking that you may simply have a weak (soft) ship's  battery.  Load test your battery or replace it if it is more than two years  old.  Or substitute a known good battery for test purposes.  If your  battery is 100% known to be in good shape, take a look at the voltage readings I  suggested in an earlier post.  Your ship's power bus or your grounding is  possibly not good enough to handle the loads you are requiring from it.

  

 Look for good, tight, corrosion free, connections made with the correct  size wire, etc.

  

 Put a digital volt meter across your avionics bus to ground and watch the  voltage as you turn on and off all of your panel items.  This  voltage reading must remain constant and above 12 volts under all  loads.  If it does not, you don't have enough battery capacity or enough  good conductor capacity to your panel's equipment.

  

 John

  

  

  

  

  

  

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