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VOR antenna and my GTN650

tcoverst

Active Member
Having trouble getting my VOR/ILS antenna showing signal on my GTN650.
The setup is flat antenna in the copilot side wingtip. BNC cable directly from the antenna (ring terminal connectors) to the back of the gtn650 (bnc connector).
It could be
1. The Antenna itself
2. The BNC cable run or connections
3. A menu item in the gtn650
I have checked the connections on the antenna and they are tight and solid. The cable was continuity tested when installed.
There is no signal when I try to tune a VOR or catch an ILS. Its not intermittent signal, its just no signal at all. The GTN 650 works perfectly for RNAVs and other gps navigation.

Open to any input someone may have for where and how to troubleshoot any aspect of this system. Particularly, I am wondering if there is a gtn650 menu item that needs to be selected or something simple like that - maybe the g3xpert can weigh in?
Thanks for any assistance or ideas you have. Its in the hands of the braintrust now - no problem stands a chance there!

Tim
 
What you have is a marginal antenna, but you should get some reception.

As you verified continuity, I wonder if you checked to see if the coax was shorted (center shorted to shield). You will need to pull the GTN-650 out of the tray to do this.

Such things a simple to troubleshoot with the right antenna analyzer. This is a great ?shared tool? for your local RV group.

Carl
 
Besides the obvious of ensuring you have the CDI selected to VOR/LOC vs GPS, under the GTN setup page there is a VOR/LOC/GS config page where the Nav radio can be enabled or disabled. I'd check to see that it has been enabled.
 
There is also a discreet input pin on the GTN 650 that can be connected to a momentary push button called CDI Source Select. It allow rapid toggle selection of either VOR/GS or GPS information to the CDI unit.
 
Have you tried listening to the audio? No audio leads to a antenna/coax issue. Audio good then it?s a indication issue.

Jay
 
Some things to try

Ok - this is really helpful stuff - thanks all. I am going to check and make sure that the config is right in the gtn by checking that the vor is enabled.
I do not get any audio when I listen. If the whole thing is not enabled - that may be why. Otherwise, I will move to Jay's suggestion that a lack of audio signal means an antenna or coax problem.
I hope to get out to the hangar later today and will report back with what I find.
In the meantime, if you have other ideas, its always best to be well armed with ideas when confronting a problem - so the more the merrier!
Thanks,
Tim
 
Simple thing: verify on the back of the 650 that the antenna is plugged into the VOR location, not the com jack. I think they?re both BNC connectors.

As Carl suggested, once you get it sort-of working but not well, the next question will be ?what kind of antenna is it really?? A flat wire is not very descriptive.
 
Ok - this is really helpful stuff - thanks all. I am going to check and make sure that the config is right in the gtn by checking that the vor is enabled.
I do not get any audio when I listen. If the whole thing is not enabled - that may be why. Otherwise, I will move to Jay's suggestion that a lack of audio signal means an antenna or coax problem.
I hope to get out to the hangar later today and will report back with what I find.
In the meantime, if you have other ideas, its always best to be well armed with ideas when confronting a problem - so the more the merrier!
Thanks,
Tim

To hear Nav audio typically need to do these things: Select Nav1 on audio panel then select nav frequency (press lower right center knob) on GTN, then press upper left knob for "ident". (I think this is the correct sequence). Sorry if I'm being captain obvious.
 
Make sure the coax is not grounding to the shield. If that is the case it would show conductor continuity even though the shield is grounding it out...
 
I am the installer of this antenna and radio. To answer the question of what type of antenna; this is an Archer wingtip NAV antenna in the right wingtip. I do not believe I installed the antenna into the COMM port of the 650 but it definitely should be checked. Everyone can make mistakes. I am no exception. As for the center conductor shorting to ground, again that is something I checked but Tim should verify that is true also.

Tim, please keep us updated on your findings.
 
Having trouble getting my VOR/ILS antenna showing signal on my GTN650.
The setup is flat antenna in the copilot side wingtip. BNC cable directly from the antenna (ring terminal connectors) to the back of the gtn650 (bnc connector).
It could be
1. The Antenna itself
2. The BNC cable run or connections
3. A menu item in the gtn650
I have checked the connections on the antenna and they are tight and solid. The cable was continuity tested when installed.
There is no signal when I try to tune a VOR or catch an ILS. Its not intermittent signal, its just no signal at all. The GTN 650 works perfectly for RNAVs and other gps navigation.

Open to any input someone may have for where and how to troubleshoot any aspect of this system. Particularly, I am wondering if there is a gtn650 menu item that needs to be selected or something simple like that - maybe the g3xpert can weigh in?
Thanks for any assistance or ideas you have. Its in the hands of the braintrust now - no problem stands a chance there!

Tim

Tim,
I had the same set up and was not happy with my LOC/VOR performance until I installed a bunny ears antenna on the fuselage under the horizontal stabilizer. I went from marginal reception to picking up the LOC twenty miles or better from the approach antenna. If you like strong transmitter and receiver operation, don't even think about using a wingtip antenna.
Danny King
 
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I am the installer of this antenna and radio. To answer the question of what type of antenna; this is an Archer wingtip NAV antenna in the right wingtip. I do not believe I installed the antenna into the COMM port of the 650 but it definitely should be checked. Everyone can make mistakes. I am no exception. As for the center conductor shorting to ground, again that is something I checked but Tim should verify that is true also.

Tim, please keep us updated on your findings.

I had Comm BNC connector where I didn't fully seat the center pin into the housing. It passed all the continuity checks, but I was getting a really bad VSWR. I cut off and replaced the BNC, all was good.
 
Tim,
I had the same set up and was not happy with my LOC/VOR performance until I installed a bunny ears antenna on the fuselage under the horizontal stabilizer. I went from marginal reception to picking up the LOC twenty miles or better from the approach antenna. If you like strong transmitter and receiver operation, don't even think of using a wingtip antenna.
Danny King

Sorry Danny, I disagree.

This ~$2 home brew antenna is flying on four RVs and preforms very well. I pick up VORs at 90+nm and localizers way beyond any practical range. For nosegear RVs the under the tail VOR antenna is a significant (and unnecessary) eye hazard, if not for the pilot then perhaps kids around the plane or your favorite dog. Same goes for VOR antennas on top of the VS for tail draggers.

Side note - I put nylon hose eyeball protectors on my two belly whip antennas right after landing for the same reason. I know of a ?one eye? RV-6 builder that learned about this hazard the hard way.

Antennas are not rocket science. But if you are haphazard during installation any antenna can be turned into a poor performer. I suspect less than 10% of builders actually verify the antenna/coax system resonate at the frequency of interest.

Carl
5-AB79966-ED40-4-ACE-B8-DF-95-B09982-A2-ED.jpg
 
Maybe the solution

Well, a morning of troubleshooting using your excellent suggestions as well as good help from others at the EAA hangar (shoutout chapter 563!) has revealed that the coax cable was shorting out. It passed continuity tests but did not show resistance as expected. Cut the male BNC end off and the cable tests out fine - so the problem short was in that BNC connector. New connectors are on order and once they arrive I hope to confirm that this was the problem and that all is right with the airplane once again.
Thanks again for help and suggestions from one and all.
Tim
 
Well, a morning of troubleshooting using your excellent suggestions as well as good help from others at the EAA hangar (shoutout chapter 563!) has revealed that the coax cable was shorting out. It passed continuity tests but did not show resistance as expected. Cut the male BNC end off and the cable tests out fine - so the problem short was in that BNC connector. New connectors are on order and once they arrive I hope to confirm that this was the problem and that all is right with the airplane once again.
Thanks again for help and suggestions from one and all.
Tim
Well Tim, sorry that my error in constructing that cable is turning out to be the cause for your trouble. If you make it down this way again I will be sure to take you to Braum?s. The burger and shakes are on me.
 
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