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Radio interference when receiving

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sideslip(at)tiscali.co.uk
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Posted: Tue Jan 16, 2007 5:42 am Post subject: Radio interference when receiving

I have a new Jabiru 2200 (85hp) installed in a  Murphy Maverick with an Icom IC-A200 panel mount VHFand an external antenna  mounted throughthe fuselage skin midway between the cabin and fin using the  fuselage for a groundplane.

  

 I am picking up ignition interference when  receiving which increases with engine speed.

 I have tried running the radio from an independant  power supply to eliminate installation wiring and still get the same  problem, which seems to indicate that the antenna is picking up the radiated  noise.

 The engine has suppressed ht leads to the plugs but  I am not sure about the leads to the coils.I checked the rotor arms for security  and they seem fine.

 Does anyone have any suggestions on how to cure the  problem? 

  

 Geoff Leedham



  [quote][b]

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nuckollsr(at)cox.net
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Posted: Wed Jan 17, 2007 6:38 am Post subject: Radio interference when receiving

At 01:25 PM 1/16/2007 +0000, you wrote:



I have a new Jabiru 2200 (85hp) installed in a Murphy Maverick with an Icom 

IC-A200 panel mount VHFand an external antenna mounted through the fuselage 

skin midway between the cabin and fin using the fuselage for a groundplane.



I am picking up ignition interference when receiving which increases with 

engine speed.

I have tried running the radio from an independent power supply to 

eliminate installation

wiring and still get the same problem, which seems to indicate that the 

antenna is picking

up the radiated noise.



The engine has suppressed ht leads to the plugs but I am not sure about the 

leads to

the coils.I checked the rotor arms for security and they seem fine.

Does anyone have any suggestions on how to cure the problem?



     Hmmmm . . . when problems arise from a "per-the-factory"

     ignition system installation, this can get sticky. I've

     never had occasion to get a problem ignition system

     into the lab to fix a noise problem. Our production piston

     aircraft still use the classic shielded magneto installations

     which have evolved into pretty radio-friendly products

     over the years.



     Are you on a list-server for either the Maverick, the

     engine or both? I'd also contact the service rep for

     the engine. You may find that he/she is aware of the

     occasional odd problem that's easily fixed.



     Try running from one ignition at a time. The problem

     may be isolated to a single system. If this is true,

     likelihood of it being a simple fix is improved.



     How much of the wiring is stuff that's used as-supplied

     and how much do you install? I did a quick look-see on the

     'net for the installation manual. Don't have time to chase

     it right now. Do you know where it can be acquired? I'd

     like to see the schematic for the ignition system.



     Bob . . .

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sideslip(at)tiscali.co.uk
Guest

Posted: Thu Jan 18, 2007 1:50 am Post subject: Radio interference when receiving

Hi Bob,

I  have tried running one mag at a time- same problem from either.

The ignition wiring is all installed by Jabiru only the mag kill wires have 

been installed by myself (screened wires earthing at the engine.

The plug leads are resistive car type but the leads from coils to 

distributer caps are not marked so I am not sure about these and have my 

suspicions. I will contact Jabiru to find out. Also the plugs are NGK but 

not resistive type, perhaps it might be worth me changing these.

The only drawing in the manual I can find is a very basic drawing which 

includes wiring for the Jabiru aircraft, and shows the ignition in a basic 

form ie.transistor ignition unit feeding to spark plugs.



Geoff



---

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nuckollsr(at)cox.net
Guest

Posted: Thu Jan 18, 2007 8:32 am Post subject: Radio interference when receiving

At 09:48 AM 1/18/2007 +0000, you wrote:



 	  Quote: 	
		  

<sideslip(at)tiscali.co.uk>



Hi Bob,

I  have tried running one mag at a time- same problem from either.

The ignition wiring is all installed by Jabiru only the mag kill wires 

have been installed by myself (screened wires earthing at the engine.

The plug leads are resistive car type but the leads from coils to 

distributer caps are not marked so I am not sure about these and have my 

suspicions. I will contact Jabiru to find out. Also the plugs are NGK but 

not resistive type, perhaps it might be worth me changing these.

The only drawing in the manual I can find is a very basic drawing which 

includes wiring for the Jabiru aircraft, and shows the ignition in a basic 

form ie.transistor ignition unit feeding to spark plugs.


	




  Okay, try running the engine with kill-leads totally

  disconnected at the engine end.



  Bob . . .

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khurst(at)taroom.qld.gov.
Guest

Posted: Thu Jan 18, 2007 3:34 pm Post subject: Radio interference when receiving

Geoff,



I don't remember your saying what kind of noise it is i.e.. Tick,tick .

. . .  or a Hash type noise.



I know a chap over here with a Jabiru (with Jab engine) and he had to

put an earth wire on the carburettor to stop static interference on his

radio.



Now if anybody thinks this is a load of hog wash, please don't shoot ME,

I'm only the messenger !



Cheers

Kingsley in Oz.

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