Jabiru Owners Group

Welcome to the world of Jabiru

Radio Noise on Mag

Post information on Radio, Transponder, avionics, instruments and accessories including EFIS systems.
  • Advertisement

Radio Noise on Mag

Postby NigelW » Sun Mar 01, 2015 2:38 pm

Hi everyone, I have just upgraded my radio from a Microair to Trig (with matching Transponder). I did have a professional avionics guy do the actual connections but I did the mounting etc. whilst it is a great improvement on the old radio I still have a little interference on one Mag. I spoke to the avionics guy briefly but he seems to have little interest in having a look. To a lot of you it will probably be a simple fix, could you please offer any tips. Thanks
NigelW
Contributor
Contributor
 
Posts: 34
Joined: Fri Feb 13, 2015 3:15 pm
Aircraft: Jabiru SPL450

Re: Radio Noise on Mag

Postby Garyo » Sun Mar 01, 2015 3:36 pm

I would start with the dizzy cap and arm, replace them, if no cure swop over the mags and see if it moves to the other side. Check all earths also check the mag switch connections it could be acting as an aerial.
Last resort, fit a dc to dc convertor in the radio Power supply, these generate their own isolated ground. I fitted 1 on mine, it made a massive improvement
Gary
Former Owner of
G-OMER
Jabiru 450 UL
Engine serial 1041
1 CHT sensor on No 4 under plug
No Exhaust temp sensors
No glass panel
No xponder
Microair radio
No bells and whistles
User avatar
Garyo
Site Admin
Site Admin
 
Posts: 322
Images: 4
Joined: Fri Feb 06, 2015 7:52 pm

Re: Radio Noise on Mag

Postby NigelW » Sun Mar 01, 2015 3:53 pm

Thanks for the advice Gary. I will start as you suggest with the new cap. Where would you suggest best source of supply?
There seems to be much disparity on line as to where to purchase 'pukka' parts. :shock:
NigelW
Contributor
Contributor
 
Posts: 34
Joined: Fri Feb 13, 2015 3:15 pm
Aircraft: Jabiru SPL450

Re: Radio Noise on Mag

Postby Steevo » Sun Mar 01, 2015 3:55 pm

This is a common problem but, unfortunately, not a common solution. It can take a lot of trial and error to get rid of mag noise. The problem with the Jab engine is that it is very noisy electronically. You are quite fortunate that the only noise you are getting is mag noise, alternator whine is another common one with the Jab.

I spent many months getting rid of electrical interference out of my system. Granted, I have a glass cockpit so that creates a few more problems electrically.

The first, easiest and cheapest thing is to put ferrites on the power wires going to the radio. The ferrite should be both on the positive and negative wires going to the radio and also to the intercom if you have a separate intercom. You can't just use any ferrites, they have to be ferrites that were designed for VHF noise such as these. You can also get clip-on ferrites so that you don't have to cut the wires to feed them through like these. Wind the wires through the ferrite twice and keep them tight.

Other things to try are to keep all wiring away from your antenna cable. If possible, route the antenna cable so that it isn't close to any other wires.

Failing that, you can go for noise input suppression on the main wire that goes to your live bus (or avionics bus) if you have one such as this or this.

After that, things start getting a little expensive. The ultimate solution is to isolate the entire radio from the main power supply. You can do this with a DC-DC converter. This effectively creates it's own, stabilised power supply from the main power supply but is isolated so the power being supplied to the comms (or any other sensitive avionics) is completely noise free. This is such a device but there are others. I point to this one as it's the one I have used. With this device, you have your sensitive electronics completely isolated from the battery power so no noise from other sources can leak in.

I am afraid, noise interference is a game of trial and error and no solution works the same for individual problems. I am surprised that you never had any interference issues with the Microair as it has a terrible reputation for noise interference. The Trig has a lot of noise suppression built in but Microair didn't seem to think about that when they designed it. It does suggest that the avionics guy who installed it has run different wires and the position or connection of those wires is getting interference that is being bled from somewhere else. The Microair must have been lucky.
Jabiru J160 & Jabiru SPL-450
PS Engineering PM3000 Intercom
Funke THT800H OLED/Trig TT22
Funke ATR833 OLED/Dittel KRT2
Flight DataSystems GD-40 CO Monitoring
PoweFlarm Core
PilotAware
Garmin 496 GPS and SkyDemon
MGL Xtreme EMS
TruTrak Autopilot
User avatar
Steevo
Site Admin
Site Admin
 
Posts: 236
Images: 2
Joined: Fri Feb 06, 2015 2:56 pm
Location: Wickford, Essex
Aircraft: Jabiru UL-450

Re: Radio Noise on Mag

Postby diablo » Sun Mar 01, 2015 4:10 pm

Hello Nigel,

happy to help you out if you are local. I have some good test equipment that can help identify the source of the noise which I used on Ron's UL450 to identify the source of noise on his radio. Best to start with the basics; nailing down were the noise is coming from is the first step before going through replacing bits and pieces. As steve states, it may not as straight forward as it seems but generally, good shielding and a good earth goes a long way to keeping noise at bay.

regards
dean
Sent from my "Electronic Numerical Integrator And Calculator" E-N-I-A-C
User avatar
diablo
Site Admin
Site Admin
 
Posts: 312
Joined: Fri Feb 06, 2015 8:25 pm
Aircraft: Jabiru SK 2200A 1157

Re: Radio Noise on Mag

Postby NigelW » Sun Mar 01, 2015 4:57 pm

Thanks for the replies guys. Stevo lots of options there to go at. The main reason for replacing the Microair was the poor reception. The Trig has greatly improved it and the shame is the noise is isolated to one Mag and more irritating rather than unbearable. Dean thanks for the offer. I'm based at Leicester but as the weather improves happy to meet up elsewhere. I do like the idea of trying to find the source if possible if you're up for it.
It's reassuring to get such great advice so promptly, thanks again.
NigelW
Contributor
Contributor
 
Posts: 34
Joined: Fri Feb 13, 2015 3:15 pm
Aircraft: Jabiru SPL450

Re: Radio Noise on Mag

Postby diablo » Sun Mar 01, 2015 5:41 pm

Just realized, I inadvertently wrote a rap ...

"a good shielding
and a good earth
goes a long way
to keeping noise at bay"

just need the beat now!

Roll on summer ...
Sent from my "Electronic Numerical Integrator And Calculator" E-N-I-A-C
User avatar
diablo
Site Admin
Site Admin
 
Posts: 312
Joined: Fri Feb 06, 2015 8:25 pm
Aircraft: Jabiru SK 2200A 1157

Re: Radio Noise on Mag

Postby NigelW » Sun Mar 01, 2015 6:56 pm

Can't see M&M and the boys having sleepless nights!
NigelW
Contributor
Contributor
 
Posts: 34
Joined: Fri Feb 13, 2015 3:15 pm
Aircraft: Jabiru SPL450

Re: Radio Noise on Mag

Postby skyjeep » Fri Mar 06, 2015 8:52 pm

There was a complete article on Jabiru radio noise issues which is still on the site
http://jabiruowner.co.uk/ under the section "Builders forum" - electrical and instruments - Radio Noise document

or maybe this direct link
http://jabiruowner.co.uk/Noise.doc

Alternatively on the Yahoo group, files section has the article and supporting photos and results:
https://groups.yahoo.com/neo/groups/jab ... e%20Fixes/

If anybody has other proven cures I'd like to add them.

The Mag coils used now are a different type so might behave differently. Jabiru adopted the inductive HT leads (black) which has probably improved things. The part that produces the most noise is the HT coil to distributor wire and some have replaced that with Magnecor style leads I have stayed with 2 ferrite beads clipped over each wire.

Ralph CH701 / 2200A
skyjeep
Newbie
Newbie
 
Posts: 24
Joined: Wed Feb 18, 2015 7:39 am
Aircraft: Zenair CH701 2200A

Re: Radio Noise on Mag

Postby Steevo » Fri Mar 06, 2015 9:29 pm

I swapped my red leads for black leads and it made absolutely no difference. Even trying resistor plugs made no difference. Eventually I ordered high quality plug lead wire and made my own and put shielded braid around the outside earthed to the engine on all the plug leads and the leads between the coil and distributor. I had some interesting results with that. If I didn't ground the braids, all my electronic instruments would go made, my EFIS would throw a fit. It seems the braid was pulling out the noise and transmitting it. Once the braids were earthed, the problem went away.

Anyway, after all of that, I didn't get any noise on my radio but the noise was still getting in to the audio out of my EFIS. Every time the EFIS announced anything by voice, it would be mixed with mag noise. My current solution is an Avioguard from MGL, I will report back on the results as it still has to be tested.

As it stands, my radio is dead quiet but still getting interference from the audio on the EFIS. The Avioguard went in last weekend and is being tested this weekend so I will let you know.

By the way, the Builders Forum from Vic's site has all been transferred on to here and turned in to posts. The Builders Forum section is on the main index screen.
Jabiru J160 & Jabiru SPL-450
PS Engineering PM3000 Intercom
Funke THT800H OLED/Trig TT22
Funke ATR833 OLED/Dittel KRT2
Flight DataSystems GD-40 CO Monitoring
PoweFlarm Core
PilotAware
Garmin 496 GPS and SkyDemon
MGL Xtreme EMS
TruTrak Autopilot
User avatar
Steevo
Site Admin
Site Admin
 
Posts: 236
Images: 2
Joined: Fri Feb 06, 2015 2:56 pm
Location: Wickford, Essex
Aircraft: Jabiru UL-450

Next

Return to Avionics, Radio, EFIS, Instruments & Accessories

Who is online

Users browsing this forum: No registered users and 1 guest