Radio interference when engine running

[Dave Nadler]

I have nice Lightspeed noise-cancelling headsets with Lemo plugs in ArcusM #125.
Unfortunately there is horrendous noise in the radio when the engine is running.
I know a number of other people have (or have had) this problem.

Can anybody recount how they fixed this (reduced noise emitted from engine)?

Thanks!
Best Regards, Dave

[Thomas Jobs]

Hi Dave,

We have an Arcus M (s/n 140) with radio Trig TY 91 Dual and Senheiser headset - and the interference at TO power makes the radio useless! Interference opens the radio reception (RX in display).

At start of this season we will do a serious trouble shooting to find the cause. I have prepared external antenna, external power supply and audio/mic completely separated from the glider system. Will keep you posted......

What radio do you use?

Brgds /THomas

[Dave Nadler]

Hi Thomas -

On Tuesday, February 21, 2017 at 7:04:26 AM UTC-5, Thomas Jobs wrote:

Hi Dave,

We have an Arcus M (s/n 140) with radio Trig TY 91 Dual and Senheiser headset - and the interference at TO power makes the radio useless!
Interference opens the radio reception (RX in display).

Same with my radio (RX display blinks on).
 

At start of this season we will do a serious trouble shooting to find the cause.
I have prepared external antenna, external power supply and audio/mic completely separated from the glider system.
Will keep you posted......

A good first check might be try a portable radio in the glider (no connections to electrical system).
I should do this as well.

 

What radio do you use?

As you, Trig TY91 with dual controls.

Looking forward to hearing your results!

Thanks,
Best Regards, Dave

[Thomas Jobs]

Hmm, Trig seems to be a bad selection. Ok, let you know when we have done our troubleshooting (end march).

Den måndag 20 februari 2017 kl. 21:58:27 UTC+1 skrev Dave Nadler:

[Dave Nadler]

On Tuesday, February 21, 2017 at 1:58:47 PM UTC-5, Thomas Jobs wrote:

Hmm, Trig seems to be a bad selection.
Ok, let you know when we have done our troubleshooting (end march).

People have this problem with other radios as well; not a Trig problem...

[Errante]

I change the squelch level of the radio, so engine noise is cancelled but still hear communications.

regards
Errante

[James Kellerman]

SPEAK UP! I CAN'T HERE YOU BECAUSE THE ENGINE IS RUNNING

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GMC2212423

[Dave Nadler]

On Wednesday, February 22, 2017 at 5:54:04 AM UTC-5, Errante wrote:

I change the squelch level of the radio, so engine noise is cancelled but still hear communications.

 
For at least a couple gliders here, reducing the squelch to where the engine isn't heard also blanks other communication...

[Thomas Jobs]

Does not help to adjust squelch, still interference...:-(

[b.aronsson]

First test I would do is to switch intercom off when the interference is there. If it goes away, the problem is mainly noise picked up by your headset microphones and the corresponding setting to adjust is the intercom threshold level. If it stays, the problem is noise introduced by wire or rf picked up by antenna (or something in the system working as one), and then the squelch level is in play. The problems in our s/n 41 with Becker 6201 and Peltor headsets is mainly microphone induced.

regards,  Bengt

[Dave Nadler]

On Wednesday, February 22, 2017 at 5:23:23 PM UTC-5, b.aronsson wrote:

First test I would do is to switch intercom off when the interference is there. If it goes away, the problem is mainly noise picked up by your headset microphones and the corresponding setting to adjust is the intercom threshold level. If it stays, the problem is noise introduced by wire or rf picked up by antenna (or something in the system working as one), and then the squelch level is in play. The problems in our s/n 41 with Becker 6201 and Peltor headsets is mainly microphone induced.

Already tested turning down the intercom; intercom is not the problem.
SH installed switch that enables headset mics and disables boom mics to prevent noise entering radio from boom mics.

We can see problem is RF because the "RX" symbol shows on the radio.
You do not see "RX" indicated on your Becker 6201?

Thanks Bengt,
Best Regards, Dave

[Jorgen Thomsen]

I have radio installation Trig TY 91  and Sennheiser headset as well, and have had terrible noise in the headset during take off.

I have located the noise to come from the spark plug heads. If you remove the heads, you will find a lot of carbon deposit from the sparks jumping to the spark plug from the head.
This is due to bad contact. The noise disappears when a good contact is established. Presently I pull each pair of spark plug heads together with a twisted tie-wrap, ensuring a good contact.

Kind regards
Jorgen Thomsen # 061

[Dave Nadler]

On Thursday, February 23, 2017 at 5:55:15 AM UTC-5, Jorgen Thomsen wrote:

I have radio installation Trig TY 91  and Sennheiser headset as well, and have had terrible noise in the headset during take off.

I have located the noise to come from the spark plug heads.

By "spark plug head", do you mean the connector on the end of the spark plug wire from the coil?
 

If you remove the heads, you will find a lot of carbon deposit from the sparks jumping to the spark plug from the head.
This is due to bad contact. The noise disappears when a good contact is established.
Presently I pull each pair of spark plug heads together with a twisted tie-wrap, ensuring a good contact.

A tie-wrap around the outside of the two spark plug connectors?
Do you by any chance have a picture?
 

Kind regards
Jorgen Thomsen # 061

Thanks Jorgen!

[Thomas Jobs]

Interesting! Thanks for the tip.....Brgds /Thomas

[Thomas Jobs]

I just remembered a detail from an Arcus M we rented in Corowa. The owner gave us this recommendation; if we have problem with rpm drop at ignition check - apply copper paste to the spark plug head to enhance contact. We never had to do it. We did not have any problems with rpm, and the radio/intercom worked perfect.......:-)

Is this approach used by anyone else in the Arcus community?

Brgds /Thomas

Den torsdag 23 februari 2017 kl. 11:55:15 UTC+1 skrev Jorgen Thomsen:

[Jorgen Thomsen]

Hi Dave and Thomas

I have attached a picture of my present setup.

Initially I put a fine copper-mesh on top of the spark plugs to make a good contact, as I found a lot of carbon deposit inside the 2 rear caps.
This immediately removed the noise. The two front caps has a natural tension with a side load, so they kept a satisfactory contact with only minimal to none carbon deposit.
After a visit to Binder, I bought from him a set of NGK caps. Binder finds them better. However I started to get noise again after maybe 5 hours of engine run.
I was out of Copper mesh, so I tried the solution with tie-wrap. It has worked fine for the last 8 hours of engine run time.
I know that Schempp-Hirth uses copper paste to give a better contact. It can be a worthwhile solution maybe together with tie-Wrap.

I have never experienced drop in RPM, even with a large amount of noise, hence bad contact.

Kind regards

Jorgen

[Thomas Jobs]

Brilliant Jörgen, thanks!

[Thomas Jobs]

One takeoff last summer I received clearance from tower, at very low altitude they radioed a changed my clearance - due to the interference it was inaudible! I told tower I have to climb for a minute and then reduce power to get rid of the interference, and then call them back. This interference is a potential safety issue - and if generated from bad spark plugs - should be fixable!

 

Has anyone reported to SH and/or Solo? Have you filed an occurrence report within you national system?

Den fredag 24 februari 2017 kl. 11:54:15 UTC+1 skrev Thomas Jobs:

Brilliant Jörgen, thanks!

[Dave Nadler]

On Friday, February 24, 2017 at 1:19:52 AM UTC-5, Thomas Jobs wrote:

....apply copper paste to the spark plug head to enhance contact.
...Is this approach used by anyone else in the Arcus community?

 
Hi Thomas - I did some research into adding conductive paste.
What I was told was:

"You must fix the mechanical problem that is causing arcing.
Otherwise, the conductive paste will degrade and make a big mess,
and you will not solve the problem. The conductive past is great
for assuring long-term connection and preventing corrosion,
but will not solve a mechanically bad connection"

It might be a good test to see if the radio noise is really caused
by a bad spark plug connection, but not a real solution.

Anybody else have further info on this?

Thanks,
Best Regards, Dave

[Dave Nadler]

Thanks Jorgen!

On Friday, February 24, 2017 at 4:58:55 AM UTC-5, Jorgen Thomsen wrote:

... After a visit to Binder, I bought from him a set of NGK caps. Binder finds them better.

Has anybody switched to screw-on connections for the spark plugs,
rather than the snap-on type? Perhaps the very large vibration of this
engine means snap-on connectors will not work for long?

Thanks,
Best Regards, Dave

[Thomas Jobs]

I really would like to check out this solution on our glider - but its not back untill end of March! Bahhhh....

Ok, will let you know My findings.......

[Dave Nadler]

On Friday, February 24, 2017 at 4:58:55 AM UTC-5, Jorgen Thomsen wrote:

...I bought from Binder a set of NGK caps. Binder finds them better.

Hi Jorgen - The cap (spark plug connector) in your picture is NGK TB05EMA, specs here:
https://www.ngk.com/product.aspx?zpid=20092
This cap has internal 5k noise-reduction resistor.
Did original cap have internal resistor? Anybody have the part number for the original cap?

Thanks!
Best Regards, Dave

[b.aronsson]

Hi Dave,

I just checked ours, and the ignition caps are from manufacturer PVL (same as the ignition coils), they are marked part nr 401222 and R=5k

Regarding the noise in our Arcus, in the initial setup of the Becker radio, we needed to use level 22 (range 6-26) for the squelch threshold, and level +9 (range -30 to +10) for the intercom vox threshold in order to keep it reasonably quiet.
But some periods we have had more problems that we have not found the reason for, this might well be the plug connector problem. When I did the annual inspection last week, I noticed the described black residue in the caps and on the spark plugs, cleaned it up and changed plugs. Yesterday the guy who did the checkflight after annual told me the radio was perfectly quiet for the whole engine run, which he has not experienced recently, so probably we also had this cap contact problem.

// Bengt

[Thomas Jobs]

Good info Bengt! Here link to PVL website. http://www.pvl-zuendungen.de/cms-en/

[Dave Nadler]

I talked to a very helpful technical support person at NGK, who says:

1) Check that the spark plug nut is tight.
Fretting, wear, and loose cap can be caused by loose nut.
No torque spec, but:
- if you can loosen with your finger, too loose.
- do NOT add any compound under nut (locktite, anti-seize, etc), must be clean!

- tighten with a pair of needle-nose

2) For high vibration applications NGK strongly recommend either:
a) Best: use spark plug terminal stud (no nut) connection.
b) Next best: spark plug with solid terminal (as opposed to screw-off nut)
not available for our application?
 
Jorgen used Binder-recommended NGK TB05EMA.
Code for terminal stud version would be NGK TB05FMA - which does not exist, so...

Next recommendation is NGK LB05FP
This has a slightly longer collar over the wire; may be too large???

Meanwhile, mechanic here says "Dave, I noticed your front spark plug cap is
kinda loose and there was a lot of black residue on top of the plug. RPMs
AOK but keep an eye on this." Hmmm...

I'm ordering some of the NGK LB05FP and will see if they fit OK.

Any thoughts???
Thanks,
Best Regards, Dave

PS: I also got a warning from NGK tech support that purchasing parts via ebay
or Amazon will likely get you Chinese crap imitations, like the one sitting on the
tech-support person's desk...
Previously received the same warning from SH regarding the Bosch W5AC plugs.
I'll make sure to order via authorized dealer.

[Thomas Jobs]

Good info Dave, thanks! Lett us know your experience.....

Brgds /Thomas

[Dave Nadler]

Today I installed and flew with NGK LB05FP spark plug caps.
Still some radio noise, but much much better and no problem to use radio now.
I had to install new plugs as spark plug nuts were glued to plugs (Locktite?? Bad!).

I will do a complete write-up and post here in the next few days.

Thanks all for your help especially Jorgen, Bengt, Biggo, and Oliver,
Best Regards, Dave

http://www.onlinecontest.org/olc-2.0/gliding/daily.html?st=olc&rt=olc&df=&sp=2017&c=C0&sc=

[Kees Van Schaick]

Hi all,
I experience terrible noise as well, as described, during take off. Radio inaudible. I have KRT2 radio with dynamic boom mikes and Sennheiser headsets. Do all of you who have reported issues with radio noise solved it meanwhile with different or cleaned up spark plugs, by fastening them with tie-waps or else have found a good solution? Many thanks for your kind advice in advance.

[Thomas Jobs]

Hi Kees,

We replaced the spark plug caps with the recommended NGK. In addition, to reduce vibrations on the caps we use a tyrap between spark plugs and then one more to create extra tension, see picture.

This has reduced noise both on intercom and when receiving radio calls. Actually it is almost perfect :-)

Brgds /Thomas 

[Mark B]

Does anyone have more experiences or suggestions to report? I am still very bad interference from the engine. The UK agent who signs off my annual has been reluctant to make changes at the plug end.

[Chester Fitchett]

Do you have access to a handheld radio that you can plug your headset into?  Would be interesting to know if the ignition noise is being picked up by the antenna, or is coupling into the coax cable running to the radio from the tail.  Since a handheld radio doesn't have the long cable and has it's own power supply, it would be interesting to see if a handheld does much better than the built in radio.  You may also be able to use the handheld antenna as a sort of probe, perhaps identifying if one spark plug cable is substantially noisier than others.  Of course, you could also just use the mag check to shut down two plugs at a time, and see if one set is particularly worse than the other.

I'll give it a try myself.

Obviously, stay aware while poking around that there is a propeller inches away.

Chester

[John Iacobucci]

I had a lot of noise with my radio (Walter Dittel) which was installed by the S-H factory with my Ventus 2CXM, during the communications involved with self launching.  I researched almost everything written on the subject.  I eventually replaced the factory spark plug caps with NGK resistance caps (metal instead of rubber) and that made a significant difference.  Then I purchased a Zulu Lightspeed noise-cancelling headset and it made further improvements.  BTW, I recently inspected a new Ventus 3M self launcher and the spark plugs were capped with metal caps that looked identical to the NGK resistance caps I installed on my Ventus self launcher.  Other likely problems are arcing between spark plug and cap which is evident with black carbon deposits on the spark plugs.  Solve with copper paste or fine copper mesh as an interface, preventing arcing.  The noise is multifactorial.  RF feedback through the microphone, whether headset or boom mike, ignition cables, spark plugs etc.  I finally reduced my noise problem to a reasonable intelligible level but still not perfect.

[Thomas Jobs]

Hi John,

Could you post the part number on the metall NGK caps. Thanks!

As I wrote earlier I have used NGK bakelit caps. Reduces noise but they are fragile and the bakelit cracks.

Brgds /Thomas

[John Galloway]

Ignoring certification issues for the sake of discussion  - if one were to fit  NGK LB05FP plug caps would resistor spark plugs provide any additional benefit?   The NGK Iridium IX BR7HIX (7067) plug has a 5kOhm resistor and seems to be an equivalent to the Bosh W5ac

[John Iacobucci]

For those having radio noise with the engine running, I suggest a read of the following article:  https://www.streetmusclemag.com/tech-stories/the-invisible-enemy-under-your-hood/

son't buy resistor caps from Amazon as you will get cheap Chinese replicas that are junk.  Google "metal spark plug cap resistor caps" and you find a plethora of suppliers of the real deal.  And yes, I used NGK iridium plugs and it did make a some difference.

Read the article.

[Daniel GUEDON]

Had some level of noise in the radio, easily blanked by adjusting the squelch level. Having no comparison point, I did not worry so much.

Then, while checking the spark plug caps I noticed a quite important amount of soot inside each cap and at the connection top of each spark plug,  most probably coming from sparks happening there, bad connection. 

Sparks plug caps are original ones.

Any one noticed the soot also ?

[Jorgen Thomsen]

Hi Daniel

I have experienced exactly the same as you. A lot of soot inside the rear caps and radio interference.

I fixed it initially by adding a fine copper web on top of the spark plug, stopping the sparking inside the caps. This also stopped the radio noise.

I took up the issue with Binder. They use NGK caps, and I have replaced mine to this brand. TB05EMA stock no 8636(black).

I make sure they sit tight, the rear ones I tie together in figure 8 with a cable binder, and I have not had any issue since.

Kind regards

Jorgen # 061

[Henrik Holm Kristensen]

Hi Daniel

We see the same on our Arcus M.

We change the caps from time to time.

To make the problem a bit less, we have put plastic straps between them, to force them together,

and by that way minimize the play in the contact areas.

Found the solution in a post in this group.

This helps quite a bit on the radio noise.

Br Henrik

Arcus no 58

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[Rod Witter]

Probably arcing at the plug caps.

Try changing to the type which doesn't grip the thimble.  You take off the thimble and the new cap has a blade which seats at the bottom of the threads.

E.G. NGK  LZFH

I don't know the significance of 1K ohm   or  5 K ohm resistance plug caps ??

Maybe this part number is not in the Maintenance manual, so it will be unauthorised !