jabiru radio noise

[Jabiru j430]

Hi my name is Rob and this is my first post and hoping someone can help as I am at my wits end trying to solve this problem.

 

I have a clicking noise on my Trig radio, the remote sender is behind the rear seat, it is rev related and will increase with rpm, I have renewed rotor arms and plug leads, it is much worse on left mag but sometimes will change to both when flying, all wires are screened.

 

I used hand held radio inside the plane and could still hear the noise and so its not wiring to headsets, any help would be much apreciated.

 

 

[wideblueyonder]

Hi

 

Hi my name is Rob and this is my first post and hoping someone can help as I am at my wits end trying to solve this problem.I have a clicking noise on my Trig radio, the remote sender is behind the rear seat, it is rev related and will increase with rpm, I have renewed rotor arms and plug leads, it is much worse on left mag but sometimes will change to both when flying, all wires are screened.I used hand held radio inside the plane and could still hear the noise and so its not wiring to headsets, any help would be much apreciated.

Hi Rob,It's going to be a process of elimination, bit by bit. Try borrowing someone else's voltage regulator if you can, for a start and see if that changes anything. A failing component like a capacitor might be the culprit, still allowing the unit to regulate, but with noise.

 

Be sure your plug leads, if shielded, are only shielded on one end.

 

There should be a noise filter fitted to the power supply wiring to your radio. Again, try a substitute filter to eliminate that as a source.

 

Let us know how you get on with finding the fault.

 

Wby

 

 

[Yenn]

The fact that the noise is a ticking would lead me to suspect it is ignition, rather than the charging system.

 

Are your P leads fully shielded?

 

 

[Jaba-who]

Hi Rob.

 

Your problem unfortunately is par for the course. I have a jab 430 with dual micro airs ( though I have just bought two mgl V6 s which I’m yet to install. )

 

I’ve had the aircraft for about 11 years and have had endless issues with noise. I have spent hundreds of hours in that time gradually whittling down the noise to a tolerable level. It seems I have a bad combination. Jabiru engines are quite noisy (electrically) and micro airs are very susceptible to noise.

 

The first bit of bad news is that you are going to have to just start at some point and try various options and see what difference they make. It is likely that you will not succeed in removing the noise completely but you will knock it down a bit with each thing you do.

 

Essentially people will jump up and tell you they have the single answer that will fix it all but my experience is that never happens.

 

There is an article specifically about it. somewhere on the jab (Australian) website or in one of the construction manuals that’s useful and also one on the USA jab site.

 

Do lots of reading and searching and make a list and try them. As you do cross them off and make notes as to what effect if any they make.

 

The potential fixes include:

 

Ferrite filters on all the wires as they come through the firewall.

 

Re-wire the radios so they go direct to and from battery ( only via switches and circuit breakers- but not to common power buses.

 

Shielded wires on all wires to/from radios, headsets etc. the shielding should only be earthed at the radio end not both ends to limit formation of ground loops. Read up or look at YouTube vids on ground loops and fixing them.

 

A big capacitor filter on regulator

 

Change all high tension leads to high quality ones

 

Clean the distributer points and pull apart clean and rejoin all inline connectors on the power circuits from the engine to regulator to battery. etc.

 

Physically separate all wires to radios, headsets etc away from any that carry any power or even better away from all other wires.

 

Off the top of my head can’t think of all the things I did over those years.

 

I can vouch for a couple of things that didn’t work.

 

I made complete shielding for all the high tension leads and also enclosed the coils in copper foil. All that did was made my engine not start. Weird because it would start some times and others not at all till I pulled the copper shielding off and it started fine.

 

You’ll find many things that some people swear by but they make no difference or maybe a little difference. The big capacitor was advised by a techno who swore it fixed the problem every time. Didn’t. And in fact I spoke to others who said the techie told them same story and they had same result as me.

 

Overall there are heaps of solutions but I found nothing fixed the problem completely. I got a little bit with many till I got to a point where I decided it was good enough and stopped.

 

 

[ruffasguts]

jay car $15.00

 

have used these in alot of applications including sending one to Florida for the prototype Thatcher CX5 cheap and easy starting polnt

 

10A DC Noise Filter (Improved)

 

CAT.NO: AA3074

 

Mick W

 

 

[frank marriott]

Had some transponder noise in 2 J230s elimted by changing the coax to commercial grade, RG58 from memory.

 

Worth considering.

 

 

[Jaba-who]

Had some transponder noise in 2 J230s elimted by changing the coax to commercial grade, RG58 from memory.Worth considering.

Yep I’d agree with you on that Frank. Although it’s the other way round. Go FROM RG58 TO (double shielded) RG400.As best I recall that made a noticible difference on mine. Well worth the extra expense for the high quality coax.

 

 

[Guest nicephotog]

Aviation grade "spark plug suppression leads" never hurt.

 

Sparker timing points capacitor on the distributor is operating?

 

Checking the "alternator" does not have problems? also.

 

The coax for high grade UHF CB heavy core heavy shield a good idea.

 

 

[Yenn]

Funny thing I have a Jab 2200 and it is just about radio silent. Not by my good design, because I know little. Are the P leads shielded? Also have you checked all your earth connections, just give them a twist and they should change if there is any problem.

 

 

[gibby]

I had similar problems with a 230, I had a Garmin sl30 nav comm and a microair, tried everything, had avionics guys look at it and they all said low voltage. The only way I could fix it was sell it, and that fixed it!

 

 

[Ayecapt]

Hi my name is Rob and this is my first post and hoping someone can help as I am at my wits end trying to solve this problem.I have a clicking noise on my Trig radio, the remote sender is behind the rear seat, it is rev related and will increase with rpm, I have renewed rotor arms and plug leads, it is much worse on left mag but sometimes will change to both when flying, all wires are screened.I used hand held radio inside the plane and could still hear the noise and so its not wiring to headsets, any help would be much apreciated.

Fibre glass! Causes more problems with radios than enough! Call me crazy.!! All 1/4 wave aerials as used on our 120mHz radios require a ground plane to replace the missing 1/4 wave of the aerial. If thes aerials do not have a good ground plane the front end of the radio will increase its gain and become susceptible to interferance . Fibre glass motor homes can suffer from a similar issue with receiving broadcast band signals when signals are weak .No radio issues are easily solved via a forum. But by ensuring that your aerial is correctly terminated into a ground plane and that your coax cable is good quality , with its screen electrically bonded (attached ) to the ground plane is a start.

 

So google ground planes and 1/4 wave aerials and check yours out.

 

You can make a simple ground plane from thin alum sheet. This may not be a fix but most rf noise enters via the antenna so make sure the aerial is installed correctly.

 

 

[Ayecapt]

Funny thing I have a Jab 2200 and it is just about radio silent. Not by my good design, because I know little. Are the P leads shielded? Also have you checked all your earth connections, just give them a twist and they should change if there is any problem.

Rf interferance is crazy, 2 identical installations can give one perfect radio and the other a dud! All your points made are very valid.

[Jaba-who]

That’s been a common solution to the problem. Go for a different brand radio. Doesn’t always work though. Have a mate who had a microair. Same troubles. Tried everything and got it moderately better but unhappy. Bought a Becker installed it. Worse!

 

Tried to fix it without success. Went back to the microair.

 

 

[Jaba-who]

Fibre glass! Causes more problems with radios than enough! Call me crazy.!! All 1/4 wave aerials as used on our 120mHz radios require a ground plane to replace the missing 1/4 wave of the aerial. If thes aerials do not have a good ground plane the front end of the radio will increase its gain and become susceptible to interferance . Fibre glass motor homes can suffer from a similar issue with receiving broadcast band signals when signals are weak .No radio issues are easily solved via a forum. But by ensuring that your aerial is correctly terminated into a ground plane and that your coax cable is good quality , with its screen electrically bonded (attached ) to the ground plane is a start.So google ground planes and 1/4 wave aerials and check yours out.

 

You can make a simple ground plane from thin alum sheet. This may not be a fix but most rf noise enters via the antenna so make sure the aerial is installed correctly.

Issues of fibreglass and lack of body for a ground plane are Not applicable in jabs set up in the “normal” way. They use a vertical dipole antenna installed in the vertical stabilizer.

[kgwilson]

I had a bit of noise in the Microair 760 radio on my Jab engined aircraft but put up with it till somehow it just got worse. My A/C was a kit and wiring was supplied and labelled. None of the radio comms cables were shielded but I used them anyway but installed a power filter & ferrite chokes at the radio and headset jacks. The whole issue got unacceptable when I was in the circuit & an incoming A/C heard nothing & all I heard was a garbled message & barely heard the aerodrome name.

 

I pulled everything out and replaced all of the comms cables including the PTT with shielded cable as per the Microair manual I should have followed in the first place. I was a bit worried that the cable was a bit thin (should be 22 AWG) as the metric equivalent from Jaycar was slightly less than this. It cost less than $20.00 including new ferrite chokes and 15 pin D-sub connector. The headset cables are approx 2.5 metres in length. I now have a superbly functioning radio & can easily be heard and understood & hear other A/C even at a distance without noise or distortion. One advantage I think I may have is that there is well over a metre from the firewall to the panel, whereas a Jabiru panel is practically on top of the firewall so EMC interference is reduced. My aircraft is all aluminium so has a whip aerial cut to length about mid way between 118 & 136 MHZ.

 

I don't know if this is of any help but at least it is a success story.

 

 

[Kyle Communications]

DC electrical noise can be reduced a lot or even stopped by lots and lots of work and trying all different stuff but if it is RF based noise forget it ..you are wasting your time. The easiest way to determin this is run the engine and check your noise..while this is happening remove the antenna connector at the radio..its a BNC type so a half twist to unlock and remove...if the noise stops...then I am afraid your chasing your tail for nothing.

 

 

[ROGER.G]

Hi my name is Rob and this is my first post and hoping someone can help as I am at my wits end trying to solve this problem.I have a clicking noise on my Trig radio, the remote sender is behind the rear seat, it is rev related and will increase with rpm, I have renewed rotor arms and plug leads, it is much worse on left mag but sometimes will change to both when flying, all wires are screened.I used hand held radio inside the plane and could still hear the noise and so its not wiring to headsets, any help would be much apreciated.

had endless radio noise problems with my SP6, once one issue apparently sorted another would manifest itself. Using shielded wire for EVERYTHING related to the radio, and making sure the wires from the tacho sender were twisted all the way seems to have fixed things, no problems for the last 5 years.

[Jabiru j430]

Rob Here again, re j430 radio noise, I have a new radio 833 which re much more sensitive than the old 25KH, I have replaced the distributer caps, the rotor arms,the ignition leads, screened the leads,screened everything I could, replace coil packs, absolutely no improvement at all.

 

In desperation I covered the entire engine in tin foil as an experiment to contain the interference and it worked, I then remove it and sprayed the entire engine bay with a screening spray and I now have a quiet radio.  I could not fix the problem but I have fixed the symptons. I will be happy to share the spray used if anyone is interested.

 

 

[Ayecapt]

Hi Rob. In effect you have built a faraday cage from your engine bay.  Faraday cages are used by scientists and technicians to isolate radio signals .    You have proven that your issue starts at your aerial and coaxial cable ,   It is receiving the hash generated by the engine systems..

 

static and noise that enters through the aerial usualy points to a poorly installed aerial.

 

its the opposite of what you might expect, a good installation allows the front end amplifiers in your radio to automatically winde back their sensitivity.    This iimproves the signal to noise ratio so that when a voice communication comes in it swamps the engine noise.

 

a poor antenna and coax does the opposite  it causes the amplifiers to crank up, and  amplify the much weaker engine noise signals.

 

. so as you say you have cured the symtoms  but have not gotten to the root cause .

 

the spray ( paint you used)  is normally finely ground metal particles suspended in a  laquer or similar.  It can be very effective . It will be interesting to see how well it sticks after a few months of heating and cooling.

 

i have used it in marine applications to stop radar signals from entering equipment sensors on ships , but these were free of vibration and large temperature changes. . Hope it continues to work but be prepared to touch up sometimes.

 

at least now you can fly in peace lol..  but look more closely at the aerial install. Particulary is the coax shield grounded to a aluminium ground plane under the base of the aerial. 

 

 

[Jaba-who]

Rob Here again, re j430 radio noise, I have a new radio 833 which re much more sensitive than the old 25KH, I have replaced the distributer caps, the rotor arms,the ignition leads, screened the leads,screened everything I could, replace coil packs, absolutely no improvement at all.In desperation I covered the entire engine in tin foil as an experiment to contain the interference and it worked, I then remove it and sprayed the entire engine bay with a screening spray and I now have a quiet radio.  I could not fix the problem but I have fixed the symptons. I will be happy to share the spray used if anyone is interested.

Can you tell me what the shielding paint is ( name, where you got it from etc) 

ill give it it a go. 

 

I am about to do a complete instrument/dash reinstall and have got new MGL radios. So maybe I won’t need it with the new radios. But if I do I’ll give it a go. 

 

 

[Jabiru j430]

the spray that I used was purchased from RS supplies in the UK and code is 841AR-aerosol 841AR340G

 

 

[Jaba-who]

Thanks for that. I’ll chase it up. 

 

How many cans did you need and did you do the entire engine bay or just the back half or so of the cowls? 

 

 

[CL Flyer]

Hi Rob,

 

             I have a good friend who has a J430 aircraft. From day one it was plagued with radio ignition noise. We tried all the usual fixes with little or no results. I did some experiments at home and the source of the problem became apparent. The problem is the negative side of the electrical system, that's why anything done to the positive side of the electrical system yielded no results. Essentially what happens is, the ignition units and the firewall act like transmitters and a  semi tuned aerial system. So all Jab aircraft have a built in transmitter and aerial  in the negative earth system. This happens because there is a thin sheet metal firewall attached to a non metal fuselage. In a metal airplane the charges leak into the rest of the airplane. In a non metal airplane, the charges radiate off the sharp edges of the firewall. Any radio worth it's salt could hear it.

 

 There are some individual differences because of holes cut through the firewall for cables and controls. The particular size of the firewall tunes it to the ignition boxes.

 

 Other non metal aircraft with  jab engines may experience the same radio noise.

 

 Fixing the problem, turned out to be fairly easy.  The firewall was taken out of the earth system (electrically) and becomes electrically inert.  All braided cables and controls have to be insulated off the firewall not just the battery cables. The end point comes, when a multimeter across the engine and firewall shows an open circuit.  This modification dubbed the "Rochedale modification"  was carried out on the J430. No more radio noise.!

 

 All the ferrite clamps were thrown out.

 

 Regards

 

 CL flyer

 

 

[Jabiru j430]

Thanks for that advice, I sorted my noise by using a fully screened it leads set  all perfectly clear now. Regards rpb

 

 

[Jaba-who]

Hi Rob,

             I have a good friend who has a J430 aircraft. From day one it was plagued with radio ignition noise. We tried all the usual fixes with little or no results. I did some experiments at home and the source of the problem became apparent. The problem is the negative side of the electrical system, that's why anything done to the positive side of the electrical system yielded no results. Essentially what happens is, the ignition units and the firewall act like transmitters and a  semi tuned aerial system. So all Jab aircraft have a built in transmitter and aerial  in the negative earth system. This happens because there is a thin sheet metal firewall attached to a non metal fuselage. In a metal airplane the charges leak into the rest of the airplane. In a non metal airplane, the charges radiate off the sharp edges of the firewall. Any radio worth it's salt could hear it.

 

 There are some individual differences because of holes cut through the firewall for cables and controls. The particular size of the firewall tunes it to the ignition boxes.

 

 Other non metal aircraft with  jab engines may experience the same radio noise.

 

 Fixing the problem, turned out to be fairly easy.  The firewall was taken out of the earth system (electrically) and becomes electrically inert.  All braided cables and controls have to be insulated off the firewall not just the battery cables. The end point comes, when a multimeter across the engine and firewall shows an open circuit.  This modification dubbed the "Rochedale modification"  was carried out on the J430. No more radio noise.!

 

 All the ferrite clamps were thrown out.

 

 Regards

 

 CL flyer

Did you need to do anything tricky to ensure insulation between the engine, the engine mount frame and the firewall?  

 

On mine the frame bolts to the firewall so that’s a connection. 

 

Just wondering (can’t remember it’s been so long since I installed the engine) whether the big rubbers between the engine and frame were open circuit as they are.  or does it need some further insulation for where the bolts go through the frame.