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Airzen

Well Known Member
I fired up my panel for the first time today and there were couple of issues that came up.

My set up has an SL-40 radio besides GTN 650 and a GMA 240 audio panel.

1) I am noticing that when I sue SL-40 to transmit, the 'RX' symbol on GTN 650 is lighting up (irrespective of the frequency SL-40 is transmitting on. And GTN 650 is not tuned to SL-40's frequency).

The audio seems to be loud and clear. But I am wondering if this has to do with "Lack of Transmit interlock" as mentioned in this thread: http://www.vansairforce.com/community/showthread.php?t=97662

Can others who have GTN 650 fired up let me know if they are seeing something similar? Any suggestions on how to tackle this?

2) The GTN 650 is not seeing any satellites. This is still from indoors (but lots of windows). The unit kept trying for over an hour without success. I checked the antenna cable and it is good. Perhaps also worth mentioning that Dynon GPS locked the signal within seconds, so not sure why the GTN unit is not getting the signal.

Any advice / suggestions? Many thanks!
 
My 430W will not lock on in the hangar. Even with both door wide open. Works great when I pull it out of the hangar.
 
There is a service bulletin for the 650 that addresses the transmit interlock. Unfortunately, you'll have to demonstrate the problem to a Garmin dealer and they'll have to send the unit back to Garmin for the update. I tried to get them to install the upgrade pre first flight, but they wouldn't do it.

I would pull the plane out of the hangar. I had similiar issues, but everything worked just fine on the ramp.
 
The WAAS antenna and GPS reciever in certified gear are nowhere near as quick to lock on as one might expect these days. It was explained to me that they favor quality over sensitivity or something similar. What you are seeing is normal. When you get the antenna a clear view of the sky, and if your cable and install are good, it will should work fine as long as there are no other issues.

What you are seeing with the radio's is what I would expect as well if you have both antennas fairly close together. In a house or hangar will also cause this. As long as there is no noise feedback, there really is no issue with it when you are using a GMA240 and you enable the feature to automatically mute the non xmitting radio's.....

While I do see the opposite radio's RX light up when I xmitt, they system is performing very well and is noise free.

Another thing to consider.....the SL40 does not have an xmit interlock either....
 
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I'm still fooling with my panel wiring but my GTN 650 locks on to the satellites within 45 seconds with good reception after booting it up while still in my workshop which is a non metal structure. I also showed the GTN 650 and GTR 225 both indicate transmitting when using the PTT but tracked that down a miss wire in my Tosten grips.:
:eek:
 
Thanks

Thanks all for the responses.

I guess I'll have to wait to see if lack of transmit lock on 650 is problematic. As Bob mentioned I can't do anything about it anyway until I am flying and can demonstrate the problem.

And will report back after I take the plane out of the shop (that has metallic floor) and see if I get the signal.
 
I couldn't get my 750 to pick up any satellites in my garage during construction. Once I moved to the airport and had clear line of sight of the sky, no issues at all.
 
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