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I noticed today my radio interference was so bad at 2800 rpm it was a struggle to hear a reply from another aircraft .  If I cut the throttle the noise disappears. How do I tell if this is ignition or alternator noise.

Also when we did the annual recently I changed to iridium plugs.

Would that cause any issues.

Tia

 

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Posted (edited)

I run iridium, no issues; make sure they are resistor type.

 

Rotax also have a 5K resistor in the screw on spark plug connectors themselves.

 

Mag test right left and see if static noise changes.

 

Diagnostic; disconnect the exciter wire for the alternator field at the voltage regulator and ground test the engine again to see if noise is gone.

 

Failed alternator capacitor may also be a source of noise.

Edited by Area-51
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Posted (edited)

Jab engine?, I had terrible RF interference on mine tried lots......Shielded P-Leads, new coils, Magnecore ignition leads, ferrites all over the place.....and finaly the thing that worked was resistor plugs.

I actually chose Iridium Resistor plugs as I thought I made loose a bit of oomph with the resistor and the finer iridium tip might regain some of that loss back...anyway all 5s on the Radio after that.

 

edit.Now I think about it I also tried a new regulator and Capacitor which made no difference, spent loads chasing that one

Edited by Red
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P.S. just looked at the logbook and the Plugs I fitted and cured the noise were NGK DR9 EIX

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16 minutes ago, Red said:

P.S. just looked at the logbook and the Plugs I fitted and cured the noise were NGK DR9 EIX

I am pretty sure that's what I fitted. Will check today. They were recommended for jabiru.

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alternator noise (the switching noise of the regulator) will vary with electrical load and state of charging of the battery, Ignition noise is directly related to rpm.

Vast majority of Jabiru noise is from ignition, Jabiru later changed the HT leads, reportedly most other improvement is had with "R" type plugs.

 

If you want to study the test data results, I wrote it up here

 

https://jabcamit.groups.io/g/main/files/Radio noise suppression

 

you might have to subscribe, there are a lot of other files there too.

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These are the plugs and leads.

Today I played around a bit with the radio and I turned the intercom off. It seems to be pretty good now.

Radio is icom a210. 

IMG20240609085238.jpg

IMG20240609085305.jpg

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Noisy radios have been with us a long time.  Shielded lead and plugs fixed it  early on R Plugs and carbon leads are a no no with Magneto's. The higher resistance makes the Coils short out internally. High altitude operations requires Coils mounted near the plug and the HT section pressurised.  Nev

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My " Fairbanks Morse " magneto specifies copper cored HT leads . I don't expect to get them from normal outlets .

Any suggestions for replacements .

spacesailor

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Posted (edited)
4 hours ago, BrendAn said:

These are the plugs and leads.

Today I played around a bit with the radio and I turned the intercom off. It seems to be pretty good now.

Radio is icom a210. 

IMG20240609085238.jpg

IMG20240609085305.jpg

Red leads are the early type, they changed to black leads at some point, I can't remember the physical difference, I replaced mine with Magnecor leads, but they didnt seem to make much difference in  setup

 

If turning the intercom off made a big change perhaps looking at shielded cables between Radio and intercom might be worth a try.(only ground the shield at one end of the lead.)

I seem to remember Icom handheld radios having a noise suppression setting, I guess you've tried that (if it still exists on the modern models)

Edited by Red
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1 hour ago, Red said:

Red leads are the early type, they changed to black leads at some point, I can't remember the physical difference, I replaced mine with Magnecor leads, but they didnt seem to make much difference in  setup

 

If turning the intercom off made a big change perhaps looking at shielded cables between Radio and intercom might be worth a try.(only ground the shield at one end of the lead.)

I seem to remember Icom handheld radios having a noise suppression setting, I guess you've tried that (if it still exists on the modern models)

The radio is an icom a210 . Not a handheld. The intercom is built into the radio. The wiring to the headset plugs is very short. It does have anl .

 

 

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12 hours ago, BrendAn said:

The radio is an icom a210 . Not a handheld. The intercom is built into the radio. The wiring to the headset plugs is very short. It does have anl .

 

 

Aah, Sorry should have googled the radio model. glad you have found an improvement but losing the intercom isnt ideal. (Fault finding radio interference is the hardest type of tinkering in my experience)

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Posted (edited)

Radio seemed fine today . Rpm didn't have any effect, the only thing I noticed was the volts were sitting on an even 14 today. When the inference was bad was when i had to jump start it . Maybe more to do with charging circuit. Anyway I will leave it alone now while it's good. 

A friend did say I should invest in anr headsets because there is so much background noise in the xair.

Edited by BrendAn
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I have an " anr " head set , it works equally well while mowing my lawn . LoL

It reduces the exhaust noise as well as electrical , while listening to a tape or radio .

spacesailor

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1 hour ago, spacesailor said:

I have an " anr " head set , it works equally well while mowing my lawn . LoL

It reduces the exhaust noise as well as electrical , while listening to a tape or radio .

spacesailor

They were going to sell them on here in the shop. I will see if they are available 

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