So very true. In times long gone, the early B-737 aircraft had the cockpit observer's audio jack located on an aluminum box next to the jump seat. The jack was insulated from the box by a phenolic insert. Inevitably, the insert would be broken by flight bags or feet entering the cockpit. Occasionally, some well-intended mechanic would fabricate a replacement insert from aluminum and install it because A, he did not have a spare on hand, and B, he was by god fixing it so it would not break again. Soon after, the crew would report noise on the interphone, and the avionics type would have to fix it. They knew where to look for the source of the problem.

Love this guy. Explains everything with easy to understand instructions.

Blimey I've been a radar engineer for years and dabbled with homebuilds and no publication has explained ground loops aswell as this!!! Also your explanation of fitting the screen to the radio end rather than the socket end is crucial advice! That explains why a Jabiru 400 I built 20 years ago always has noisy comms because I remember naively connecting the screen to both ends of the audio cables PLUS I didn't use the fibre washers to insulate the jack sockets from aircraft ground 🙄 Currently building a Eurofox 914 Turbo so the comms is now going to be excellent and spot on I'm sure!!! Back to building 🤠

Considering I'm planning an all composite build, this gave me food for thought about how I'll need to go about creating good grounds while simultaneously preventing galvanism between the carbon fiber and wiring fixtures, jacks and plugs.

Jon, I find the way you talk gentle, precise and it helps me understand better the point you want to make. I enjoy your videos, the way you make them and the lessons that they carry. Thank you so much for all your efforts.

You can speed this up to 1.5x in lieu of heavy medication, or... here's the shortest version: to protect against RF energy/interference, land the drain wire for cable shielding at ONLY one end - the other needs to be unconnected and insulated [drain wires do not come with insulation, as they must have contact with foil wrapping or mesh inside cable sheath]. The jack in this example uses an insulated conductor, which should tip us off that if there is a reference to chassis, it ought to be at a central point, not at the end device. Of note: COMmon [for various amplification setups] is not necessarily chassis ground - don't tie the two together [unless indicated]... but if you're that deep, you probably already have schematics in hand.

After trying to run down my problem, and talking with even the manufacturer, no one offered this solution to me. Months of struggles were simply solved by watching this video. I guess the solution was so simple that no one though to bring it up, Thank you

Thanks for your time and for illustrating me about this topic, very helpful. Easy to understand. Greetings.

Great video! You reduced the problem to a simple diagram to make it much easier to see the issue AND the solution. Kudos also to James Wills for his suggestion of fiber washers with a shoulder to positively isolate the ground braid on the microphone/earphone plugs.

Excellent. I had a new audio panel installed in my Cessna 182 by a certified installer. Horrific engine noise! They were no help, so I began going through the installation manuals, which emphasized that the ground braids for the 4 mic/phone plugs should be grounded at ONLY ONE END (at the radio), NEVER BOTH. To accomplish this, the jacks were to be installed with two-piece fiber washers which had a shoulder that protruded through the mounting holes so they didn't make electrical contact. Of eight jacks (4 mic and 4 phone), only two were installed right. Some had one part of the fiber washer, some had the other half, some had none. I called the installer in Clarksburg, WV, and they told me they did a good job and couldn't/wouldn't help me. I bought the proper washers and reinstalled all eight jacks. No noise at all now. Never trust anybody.

Such an awesome and thorough explanation. Thank you!

Great videos Jon. You are my go to guy when I need some help (on par with "EAA hints for homebuilders"). Your instruction provides the rationale (which is why we build) as well as the "how to". At first I was taken back by the Mr. Fred Rogers slow pace delivery, but when I set the playback speed to 1.25 speed it is no longer an issue. Don't change a thing.

Simple, yet informative...well done.

Great tip, Jon. Thanks again!

Fantastic video, after installing strobe lights to my common ground (cigaret lighter plug) all looked like working great ....ready for flying next day ...but horrible static noise just from intercom no radio attached. Thanks again for the video!

that was really fun and educational to watch! thanks!

Hi, Great Video !!! Great Explanation ! - And thanks for visiting in Oshkosh! Regards from Alaska!

Thank you for sharing this great video.

Thanks for that very important information! Well explained!

Very interesting and informative, thank you for posting sir.

Great video .. Your channel is fantastic. Well done.

Nice video. Thanks for taking the time to make this.

Great explanation I guess I have one going bad I will be checking these washers.

Awesome as usual. Thank you for the tips

Every video I see from this guy seems to be a video designed for an elementary student. I'm not talking about the information; I'm talking about the presentation.

you learn something new evefyday !! thanks buddy !

While I agree with what you recommend to do, I don't quite buy the antenna theory as an explanation. Stub wires (which you now created) make excellent antennas, and high frequency can anyway easily jump across the insulating washer as it is a capacitor that has very little resistance at high frequencies. What you are trying to avoid is a sensitive device (amplifier) using a ground point that is not fixed at very flat 0 Volt, instead has a small signal that is caused by some other device's return current. If that some other device has a current draw that is not steady, it will make that ground point noisy. The non steadiness of consumption might come already from the alternator raising the bus voltage every so slightly at its frequency as it pumps current into the battery/system when the diodes open up. So if you have a Y constellation in your ground wiring (not a common ground point), the device on one arm will raise the voltage in the junction point of the Y according to the current it draws and the second device on the other arm will not see ground itself but the raised ground at the junction point.

Thank you so much !! So informative !!

Nice video sir please make some more its very interested !!!

I love it!!!!Everyone back to building!!!

Thanks I appreciate the information on that have noise in my headset when I click mi mic I will chick it out tomorrow and see if I can solve it now! 😎

Thank you so much

Very informative

Thank you, an interesting lecture

Just don't connect the shield to the headset jacks at all, only connect it to ground on the radio end. That is what the install manual that came with my radio said to do.

Thanks for great info. However, I use portable radio with intercom in my powered parachute. When my LED navigation or landing lights are on, I get a lot of static. Can you please help me for this scenario. Thank you in advance.

Very well done. I need to run a 12 volt battery heavy wire through the bulkhead. Do you have any videos showing how that is done? Can I just use a grommet or do I need something more exotic?

I looked up the website and canto find t ca you paste a link please. Thank you. Great video.

Hi, your video about ground loop was very informative and helpful. When I installed GNC 255, I faced the noise problem and now realised what to do. Thanks a lot. On a PA 28-181, which on is the best ground point for all radios?

nice!

I have a Cessna 182 that had extensive avionics and radio replacements. I am getting some serious alternator noise through my headsets. The noise is now worse just after an install of a couple Garmin G5's. My Avionics shop said I need to replace the Alternator and regulator and if that doesn't help my problem I should bring the plane to him to trace down the problem. I know throwing parts at it is one way of doing it but not the way I want to go about it. Can a ground loop pick up this alternator noise? I plan to put my electrical system on an oscilloscope to check Alternator Ripple and make sure I don't have a bad diode but I really don't think that is the problem. Any thoughts that could help me trace this issue down? The video was very easy to understand and I am going to take a look at my communication jacks to make sure they are not grounded to where they are mounted to as well.

Those washers at 7:02 would only work if they, either protruded into the hole or aligned the thread precisely so that it wasn't touching the metal...a small length (panel thickness + washer thickness) of heatshrink over the thread works well.

Is the shielding connected to the headsets, or can that wire just be clipped & not attach to the RCA headphone jack?

How do you make sure that the part of the jack that passes through the hole in the grounded metal frame does not touch the walls of the hole?

I asked Bendix tech about single point grounding P lead shields and was told that turns the conductor into an RF antenna!

Would it be a good idea to run all grounds to the same ground bus but have a amperage ground bus for all radio and audio equipment? In other words, should the audio grounds be separated/isolated from the rest?

Or you could not connect the shield to the black wire at the jack. Only connect the ground at the radio. Simple and easier solution.

I think DC electricity flows from the negative terminal to the positive. Negative = excess free uncaptured electrons. Positive = chemical / element lacking and wanting an electron in a open orbit state around it. So the electricity would travel through the frame of your car or airplane, to your device, and then back to the positive terminal of your battery.\ choppergirl.air-war.org

So instead of using a rubber washers why not just cut the negative wire?

I used a piece of carbon fiber sheet stock which insulated all four jacks..

I understood you should never use the airframe as ground. Run separate lines to a common ground.

wow whos the beautiful red head ?