Troubleshooting NAV antenna

[Winger67]

I have a Garmin 430W where the NAV radio isn't receiving. No indication of a VOR or LOC on GI 275 HSI and nothing but static when trying to ID the audio morse code. Having a shop look into it tomorrow but tried to do some basic troubleshooting myself with a multimeter. Should the two sides of the whisker antennas on the rudder have continuity? I was under the impression once side should be grounded and other the center conductor.

 

[wilkersk]

Hard to tell much of anything with a multimeter. You can test for continuity of the center conductor for the feed coax by disconnecting the coax at both ends. Short the center conductor to the shield on one end then put the meter leads accross the center conductor and shield on the other end of the coax. WIth the center shorted to the shield the meter should read continuity between center and shield on the other end. Then remove the short and the meter should read an open (either "OL" on a digital or something very close to the infinity symbol on an analog meter.

Reading through the balun and antenna with a multimeter won't give you any useable info. You need an antenna analyzer for that. Theres a relatively inexpensive tool out now call a NanoVNA that will give you a VSWR and Smith chart analysis of you antenna and coax. But, you're probably better off taking it to the shop at this point.

 

[brien23]

balum

 

[wilkersk]

balum

Hah! I was looking for a design for a good sleeve/choke type balun for a homemade Nav antenna. This would've been perfect. But, too late now. I already broke out my Bob Archer.

 

[Winger67]

Thanks for the help. The issue turned out to be a bad BNC connector on the coax at the splitter.

 

[Roland Donnell]

Same issue and equipment except partial indication with a few miles of the VOR. Indicator tests good. Thanks for posting the solution.