NAV reception problems

[wizard]

Some history. I had an Archer antenna in the wingtip and was only able to achieve 35 nm range. I abandoned the antenna and added cat whiskers on the bottom of the aircraft (beneath the horizontal stab) with a balun manufactured from instructions found on the Aeroelectric website. With the new antenna, I was able to achieve very good performance of up to and beyond 80 nm. Recently, I have noticed substantially decreased performance (20-30 nm max). The last time I had good performance was on an ILS approach into Newport, OR, last summer. This also happened to coincide with a changeout of my magneto to a PMAG. I recently inspected the location where the antenna is attached to the fuse and I found some stray aluminum spirals that may have been "shorting" between the two antenna wire connection studs. I vacuumed out the area and did a quick check of performance. When it appeared to be better, I though I solved the problem but probably didn't test extensively enough as I am still receiving only marginal performance. I bypassed the diplexer (providing the GS/VOR outputs) and connected the coax directly to the VOR connection on the back of the 430W. I now receive signal up to 40-50 nm, but no more. Help me decipher my troubleshooting efforts and suggest further troubleshooting or solutions. Thanks!

 

[RV6_flyer]

My Archer antenna picks up over 80 NM for more than 16-years.

You could have a radio problem, coax problem, antenna installation problem or any number of errors in the installation.

Something was wrong with your installation when you abandoned the Archer antenna. Find a friend that has the same radio you do and see if Your Radio works in their airplane and their radio works in your airplane. Once you know that, you can start checking Everything else.

 

[wizard]

Testing equipment

Is there a piece if testing equipment that is available that can test the radio, antenna, and coax on the ground?

 

[wirejock]

testing equipment

When I worked on radio equipment, I used a watt meter to test output and the coax/antenna system. Power forward and reflected is read at upper and lower freq range. There is always some reflected but it should be very little if the system is performing well.
The only way to test receive was a spectrum analyzer. I injected a signal at the low end of the freq range for the radio and turned the power down till it blanked. The same process was repeated for the upper range then the two readings compared to specs for the radio.
That said, most often problems were a faulty coax/ antenna system. Usually it was a bad ground or a short somewhere. If a watt meter is not available, a RF meter will suffice.
A Volt/Ohmeter would at least show a short or bad ground. Disconnect at the radio and read continuity from center conductor to the antenna and from center conductor to ground and from barrel to ground.