GTN Comm breaking squelch

[sjarrell]

Problem AND a solution (for a change!)

Problem:

My GTN650 was breaking squelch. The RX light was on constantly on all frequencies when it occurred, and it occurred very randomly seemingly without rhyme or reason. It was almost impossible to put a finger on when it was going to do it. It would break squelch without any of the lights on or anything else that you would normally think would cause noise.

I went into the config and raised the squelch to 75, then 80 and finally 100%. While it was doing this my SL30 was just fine and was not breaking squelch so I was certain the problem was with the GTN unit.

Today, sitting in the hangar messing with the avionics the 650 wasn't breaking squelch. Everything was fine for about the first 10 minutes, then it started up again. I was almost to the point of pulling it and sending it back to Garmin for service when I finally figured out what was causing it!

Solution:

I have a panel mount USB outlet and an iPad mount on the left side of the panel. When the iPad is plugged into the outlet AND it is charging, the GTN breaks squelch. The instant I unplug it, the noise stops. For some weird reason it doesn't seem to affect the SL30 at all.

Now it makes sense why it was so hard to track down. When the iPad isn't charging it doesn't make noise. Many times I'd fly without even plugging it in so of course it wasn't a problem then.

Now that I know that it's either the iPad or the USB outlet itself that's noisy (probably the latter) there are a lot of things that I can do to try to remedy it such as winding the 12v power conductors that feed the USB outlet through a ferrite core or even running them directly to the battery. Worst case I'll simply charge the iPad with my external USB battery if necessary.

I'm going to do a couple of tests tomorrow to see if the noise is coming from the outlet itself or from the iPad and I'll report back.

 

[Trevor778]

There is also a new software release that addresses this issue. It's service bulletin 1526.

 

[Airzen]

same problem

I too have the same issue, and its bad to the point that I use my other radio sl 40 as the primary comm.

Don't have any iPad or aux devices charging so not sure how to go about it.

Thanks for the link to the SB. Looks like Garmin admits to the problem. But I don't see how to get it fixed without spending big bucks.

 

[sjarrell]

There is also a new software release that addresses this issue. It's service bulletin 1526.

Thanks. I had looked at that before but I'm wondering if reducing "reduced random squelch breaks" would address this issue. When the iPad is charging it's not random, it's constant. I guess it's possible that this update does improve the squelch function to where it's as good as the SL30s. I'll probably just wait till the next version comes out that includes the ability for the G3X Touch to control the Com before paying to have the upgrade done.

In the meantime I'm going to try to find the source of the noise. Inquiring minds want to know!

Thanks!

 

[sjarrell]

I too have the same issue, and its bad to the point that I use my other radio sl 40 as the primary comm.

Don't have any iPad or aux devices charging so not sure how to go about it.

Thanks for the link to the SB. Looks like Garmin admits to the problem. But I don't see how to get it fixed without spending big bucks.

Have you tried going into the Setup - Com setting and increasing your squelch to 75% from the default 25%? I have read in a couple of other threads that Garmin had recommended this and it worked for other people even though that did not solve my problem.

 

[rleffler]

Have you tried going into the Setup - Com setting and increasing your squelch to 75% from the default 25%? I have read in a couple of other threads that Garmin had recommended this and it worked for other people even though that did not solve my problem.

This is only effective if all the proper updates have been installed.

 

[GalinHdz]

I have a panel mount USB outlet and an iPad mount on the left side of the panel. When the iPad is plugged into the outlet AND it is charging, the GTN breaks squelch. The instant I unplug it, the noise stops. For some weird reason it doesn't seem to affect the SL30 at all.

This is a known issue with most "cheaply built" USB outlets. Cheap has no connection with price. Change the USB port to one with better RF interference filtering and the problem goes away permanently. I wound up using a $20.00 BELKIN USB adaptor after experimenting with several different ones.

Again, cheap has no connection with price.

 

[sjarrell]

This is a known issue with most "cheaply built" USB outlets. Cheap has no connection with price. Change the USB port to one with better RF interference filtering and the problem goes away permanently. I wound up using a $20.00 BELKIN USB adaptor after experimenting with several different ones.

Again, cheap has no connection with price.

That's exactly what I'm thinking and what I'm going to try a little later today. Thanks!

 

[sjarrell]

This is only effective if all the proper updates have been installed.

Thanks Bob. From what I've learned there was an update back in 2014 that you and the Garmin field supervisor commented on in this thread that explained why the GTN breaks squelch and the older radios (a SL40 in that case) don't. I did have that update already installed as my radio was just updated a month or so ago. As I understand it the 75% setting should work on radios with that update installed.

There was a new service bulletin 1526 and a new update 2.2 released April 1, 2015 that looks like it further enhances the GTN's squelch sensitivity settings and capabilities. I'll have this installed when the new update that was mentioned at Sun-n-Fun that allows the G3X touch to control the GTN's Com is released. That will be cool!

Thanks for your help!

 

[GalinHdz]

That's exactly what I'm thinking and what I'm going to try a little later today. Thanks!

FWIW This is the Belkin 2.1A USB power connector that worked for me after testing several others. I think I paid $25.00 for it back in 2013. The best part is that it is very small so it doesn't stick out from the cigarette lighter port.

I also have a Scosche two USB power connector which also works well. I use it more in my car than in my airplane.

 

[sjarrell]

FWIW This is the Belkin 2.1A USB power connector that worked for me after testing several others. I think I paid $25.00 for it back in 2013. The best part is that it is very small so it doesn't stick out from the cigarette lighter port.

I also have a Scosche two USB power connector which also works well. I use it more in my car than in my airplane.

Thanks Galin. I ordered that one earlier today. I figured that's what you were talking about.

 

[b432291]

This thread should be a sticky, these USB power adapters are real (RF) noisemakers. If you need to rely on your comms (or like to listen to FM music) be careful with the use of USB chargers.
I ended up paying ~$190 for this:
http://www.charge4.co.uk/
At least this guy actually has a RF emissions scan to look at:
http://www.charge4.co.uk/questions-and-answers/example-measured-emissions.html
I fly out west and I sure do not need 400% added to my noise floor.
You may find a off-the-shelf $25 unit that is "quiet", but I've spent thousands on quality comm equipment, why risk it for $25?

 

[sjarrell]

This thread should be a sticky, these USB power adapters are real (RF) noisemakers. If you need to rely on your comms (or like to listen to FM music) be careful with the use of USB chargers.
I ended up paying ~$190 for this:
http://www.charge4.co.uk/
At least this guy actually has a RF emissions scan to look at:
http://www.charge4.co.uk/questions-and-answers/example-measured-emissions.html
I fly out west and I sure do not need 400% added to my noise floor.
You may find a off-the-shelf $25 unit that is "quiet", but I've spent thousands on quality comm equipment, why risk it for $25?

I can verify that the Belkin adapters shown above do not cause the GTN to break squelch. I do not have the equipment to test to see if they add to the "noise floor" or not but I can verify that they work.

Thanks!