Opinions On Whats Causing This Static?

[GeneralT001]

Ever since I received this aircraft it has had an annoying "static" issue when using the intercom actively (voice activated). Initially after engine start the problem isn't apparent but after about 10 minutes in the air it starts to become noticeable and just gets worse. It gets to the point where ATC cannot read my transmissions and its just too much to endure.

When I received the aircraft I noticed that it had two sets of jacks on the Pilots side. The first two work but do not have a voice activated mode...so I'm guessing they are an "emergency" set? The others jacks beside those two do allow the voice activated talk, so that you can hear the copilot and passengers.

In the video the static is apparent at about the :40 sec the mark...when I give up and switch to the other jacks. Any idea whats causing the static in the audio? I will be replacing everything in the fall to glass/Garmin...including audio...so that will probably solve that problem. But...curious minds want to know - in case plans change 

 

Hers a pic of the audio control that allows the Pilot/Co-Pilot to control the squelch/volume when using those jacks with voice activation (lower right side of the pic):

[Marauder]

​
As someone who chased a few static gremlins over the years; here are a few things I would look at before you get to the expensive stuff (i.e. pulling radios for bench tests).

Take a look at the insulators on the jacks. I had an issue where flight vibration would cause a static problem.

Make sure the jacks (all of them) are not touching anything. Again vibration in flight.

Pull the radios from the stack and reseat them after cleaning the connectors.

Make sure the antenna on the radios are grounded properly.

Follow the wires from the jacks to make sure they aren’t wearing or grounding somewhere.

Try turning of stuff in flight to see if you can make it go away. Had this issue due to my JPI 900:

 https://youtu.be/xOBA-FOu944

 You could be experiencing a breakdown of your RG-58 cable. I noticed this issue after my panel was upgraded. The old radios tolerated the degrading 58 cable. I had to run all new RG-400 to address this issue. When I pulled the 58 I found this kind of stuff:

​


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[PT20J]

From your description, it sounds like the problem is in the intercom. I would pull the breaker on it which will put it in fail safe mode which connects the pilot’s headset and PTT directly to the audio panel by relay without any electronics in between. If this fixes it, it is the intercom. 

Skip

AA80 InterVOX.pdf

[GeneralT001]

3 minutes ago, Marauder said:

As someone who chased a few static gremlins over the years; here are a few things I would look at before you get to the expensive stuff (i.e. pulling radios for bench tests).

Take a look at the insulators on the jacks. I had an issue where flight vibration would cause a static problem.

Make sure the jacks (all of them) are not touching anything. Again vibration in flight.

Pull the radios from the stack and reseat them after cleaning the connectors.

Make sure the antenna on the radios are grounded properly.

Follow the wires from the jacks to make sure they aren’t wearing or grounding somewhere.

Try turning of stuff in flight to see if you can make it go away. Had this issue due to my JPI 900:

https://youtu.be/xOBA-FOu944

 You could be experiencing a breakdown of your RG-58 cable. I noticed this issue after my panel was upgraded. The old radios tolerated the degrading 58 cable. I had to run all new RG-400 to address this issue. When I pulled the 58 I found this kind of stuff:




Sent from my iPhone using Tapatalk Pro

Thanks...I'm scared to look behind there

[GeneralT001]

4 minutes ago, PT20J said:

From your description, it sounds like the problem is in the intercom. I would pull the breaker on it which will put it in fail safe mode which connects the pilot’s headset and PTT directly to the audio panel by relay without any electronics in between. If this fixes it, it is the intercom. 

Skip

AA80 InterVOX.pdf 799.48 kB · 0 downloads

Thanks...I'll definitely give that a try.

[larryb]

I listened to the audio in the video. It almost sounds like the pilot ceiling air vent blowing on the mic and opening the squelch. 

[GeneralT001]

Just now, larryb said:

I listened to the audio in the video. It almost sounds like the pilot ceiling air vent blowing on the mic and opening the squelch. 

I wish it were that. But I also loose the ability to transmit/receive radio comms...ATC can't make out what I'm saying eventually.

[N201MKTurbo]

It sounds like ignition noise, so there is probably a belt and suspenders fix. The intercom probably has an improper ground somewhere. Could be the jacks, could be a broken ground on the intercom connector or an audio wire shorted to ground. On the other side of the firewall, I would check the spark plug wires and the P leads.

You will just need to troubleshoot it.

[carusoam]

Great video GT!

that should help a lot…

Best regards,

-a-

[Yetti]

Similar problem that was fixed by the copilot holding the headset plugs a certain way.   Followed up by tightening the co pilot jacks. (new install of audio panel and some tall installer must have forgotten to secure them)

The King 24 is running the front jacks and the little panel to the lower right there is running the back jacks.

Try isolating with the lower audio panel. little switch in the middle there.   That will tell you front or back jacks.    Put a headset in each of the jacks and see if one make more noise or a difference.

The jacks are supposed to be isolated from the metal with fiber washers.    The back ones probably are because they are in plastic.

The shield wires to the jacks are only grounded to the audio panel and not to the jack proper.

Also try a different headset to start.

Also you have your video camera jacked in somewhere.   Try not using it.

Also if you have a USB adapter take it out of play.

Do these one at a time so you know what it is.

Report back for next steps.

 

 

[GeneralT001]

1 minute ago, Yetti said:

Similar problem that was fixed by the copilot holding the headset plugs a certain way.   Followed up by tightening the co pilot jacks. (new install of audio panel and some tall installer must have forgotten to secure them)

The King 24 is running the front jacks and the little panel to the lower right there is running the back jacks.

Try isolating with the lower audio panel. little switch in the middle there.   That will tell you front or back jacks.    Put a headset in each of the jacks and see if one make more noise or a difference.

The jacks are supposed to be isolated from the metal with fiber washers.    The back ones probably are because they are in plastic.

The shield wires to the jacks are only grounded to the audio panel and not to the jack proper.

Also try a different headset to start.

Also you have your video camera jacked in somewhere.   Try not using it.

Also if you have a USB adapter take it out of play.

Do these one at a time so you know what it is.

Report back for next steps.

 

 

I'll work through that list....the noise was always there...camera or not

[Yetti]

2 minutes ago, GeneralT001 said:

I'll work through that list....the noise was always there...camera or not

1 down several to go.

[takair]

Have you tried shutting off various avionics.  Try the 396 in particular. Is it tied into the audio system?  I had to add a fairly large filter on mine to keep the noise down.

[Yetti]

9 hours ago, Marauder said:

As someone who chased a few static gremlins over the years; here are a few things I would look at before you get to the expensive stuff (i.e. pulling radios for bench tests).

Take a look at the insulators on the jacks. I had an issue where flight vibration would cause a static problem.

Make sure the jacks (all of them) are not touching anything. Again vibration in flight.

Pull the radios from the stack and reseat them after cleaning the connectors.

Make sure the antenna on the radios are grounded properly.

Follow the wires from the jacks to make sure they aren’t wearing or grounding somewhere.

Try turning of stuff in flight to see if you can make it go away. Had this issue due to my JPI 900:

https://youtu.be/xOBA-FOu944

 You could be experiencing a breakdown of your RG-58 cable. I noticed this issue after my panel was upgraded. The old radios tolerated the degrading 58 cable. I had to run all new RG-400 to address this issue. When I pulled the 58 I found this kind of stuff:




Sent from my iPhone using Tapatalk Pro

IT's not the antenna, it's not the antenna coax.   Not that those don't need replacing with RG400.   But you can hear it not transmitting or recieving.    and ya re rack the audio panel several times to clean the connectors.