What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Weird issue...

D

dweyant

Well Known Member
So I went out flying tonight to shoot a couple practice approaches for currency and get familiar with my net GTN650.

I had two COM issues that are a bit confusing.

1- com two (headless Garmin com) was very staticky, and hard to understand. Tried it on a couple frequencies with the same result.

2 - com one (the 650) would occasionally have the transmit icon flash when I wasn't pushing the transmit button. Also, on some frequencies (122.9 and 122.25) when I transmit on com1 it receives on com 2 (different frequency).

It was 100 degrees on the ground when I took off so that might have had something to do with it?

-Dan
 
How far apart are the antennas? What are you using for a audio panel? Does taking out the gtn fix the other com? Just some ideas to help narrow it down

Jay
 
pilot2512 said:
How far apart are the antennas? What are you using for a audio panel? Does taking out the gtn fix the other com? Just some ideas to help narrow it down

Jay
Click to expand...

Antenna's are about 3 feet apart (under wing on left and right side of fuselage).

I'm using the Garmin audio panel (everything in the plane is Garmin)

The scratchyness with the COM2 is intermittent. When I tried it on the ground about 30 minutes after I landed it was clear. Had the wife talk to me on a handheld.

-Dan
 
dweyant said:
Antenna's are about 3 feet apart (under wing on left and right side of fuselage).

I'm using the Garmin audio panel (everything in the plane is Garmin)

The scratchyness with the COM2 is intermittent. When I tried it on the ground about 30 minutes after I landed it was clear. Had the wife talk to me on a handheld.

-Dan
Click to expand...

Try it again first on the ground and then immediately threafter in the air.

Actually try two cases on the gorund. One with engien running and one without.


If it works fine on the ground, no engine but is scratchy with engine running, the check:
1. Seating of radions
2. BNC connectors for solid and firm connection as well as being well maded with no little loose wires hanging out.

Also, make sure that you have the latest softwarre updates in the Garmins.

James
 
With antennas 3 feet apart it's pretty tough to eliminate cross-talk. Use the audio panel to de-select the non-transmitting radio.
 
jclark said:
Try it again first on the ground and then immediately threafter in the air.

Actually try two cases on the gorund. One with engien running and one without.


If it works fine on the ground, no engine but is scratchy with engine running, the check:
1. Seating of radions
2. BNC connectors for solid and firm connection as well as being well maded with no little loose wires hanging out.

Also, make sure that you have the latest softwarre updates in the Garmins.

James
Click to expand...

Just did a quick test this morning (no engine run) and everything seems to work fine, including not seeing the transmit/receive issue on different frequencies.

I'll try the tests again this evening with the engine running.

And I did double check that I'm running the latest (3.70) software from Garmin.

Any other ideas between now and then would be appreciated.

-Dan
 
Dan,
I think it has been quite common for some of us with the GTN to have squelch issues. Some also have sidetone problems.
You might check again on the TX light flashing occasionally as if it is the RX light then it is a simple setup function on the radio. It comes from the factory with a very low setting. It needs raising a bit to keep from needlessly breaking squelch.
I also had to raise my sidetone quite a bit.
 
Headset plug ins

I had one fiberglass washer fail on the headset plug in on the backside of the panel. No problem on the ground but with engine running, just enough vibration that it was interfering with the audio/squelch. It was grounding out and "transmitting" static. Lots of rabbit trails to hunt down. Good luck.
Pat Garboden
Katy, TX
RV9A
N942PT
 
If you are using auto plugs make sure the connectors are seated properly. I had this issue and one of the connectors to the plug was not seated. Engine was running smoothly and mag check was good.
 
Once in awhile I have a "staticky" condition on a selected frequency. It is never a regular or continual condition. This year, I've had it happen twice, once each on two different Class D tower frequencies. Have not figured out why. As long as it's a rare condition, I'm not too worried about it.
 
Rupester said:
Once in awhile I have a "staticky" condition on a selected frequency. It is never a regular or continual condition. This year, I've had it happen twice, once each on two different Class D tower frequencies. Have not figured out why. As long as it's a rare condition, I'm not too worried about it.
Click to expand...

I read in another thread somewhere that if the static only occurs on a few frequencies, it may be related to EFIS grounding issues. Some require certain pins to be grounded in certain configurations.
 
Did some more troubleshooting tonight and here is what we have figured out.

Com1 (650) set on 122.9
Com2 (GTR) set on 122.9
Engine off

Power up panel except for 650.
Everything works fine. Transmit/receive sound good on several frequencies (GTR).

Power up 650
Audio Panel on Com2
As soon as 650 starts to power up Com2 shows receiving. Listen on headset and it sounds like a stuck mic.
After powerup 650 shows TX, but stops after a few seconds throwing an error message of a stuck mic.

I'm out of ideas other than an internal error on the 650? Anyone have anything else?

-Dan
 
Dan,

Had a similar problem in a Rans with different equipment. Finally tried different headsets which showed the problem was the headsets. The headsets giving the problem are Lightspeed ANR (I think Sierra). For a test, try using conventional headsets, no electronics or ANR.

Jim Butcher
 
I still think it is a grounding problem. Confirm the wiring is per Garmin recomendations.
 
You must log in or register to reply here.
Back
Top