15th August 2012

One problem down

Hours: 2.0 | Posted in Flight Test

Fixed the radio problem tonight, though the problem was not what I expected.  Previously, I’d swapped the feedline and antenna from the installed Comm 2, to the prewired set for Comm 1, with no change in performance.  I also removed the primer from the inside of the belly skin to provide a better ground plane; again, no difference.

Monday night, I’d ordered a different bent whip antenna, since it seemed to indicate that the problem was in either the antenna or the radio.  The antenna arrived today, so I took it to the hangar to test.  Because my antenna has a 2-bolt mounting, and the new one has the standard 4-bolt mounting, I had to drill and deburr new mounting holes to install the new one.  After installing it, I turned on the radio again and…same poor reception as before.

Frustrated now, I had to check the one last part external to the radio — the short whip installed by the dealer, which connects the 90° mating connector on the radio tray, to a female BNC for connection to the airframe antenna feedline.  After removing it, I opened the cap to the 90° connector and immediately saw that the center conductor had never been soldered; it was very nicely stripped and inserted into the proper place, but the conductor was not soldered to the connector pin.

Yep, that’ll do it…I pulled out a soldering iron and made the connection.  Reinstalled, and the AWOS now came in loud & clear in the hangar with the door closed.  A flight test plane was also inspecting the airport’s navigation signals, so they were in the area for a while, and I was able to pick them up as they moved around the area.  Interestingly enough, this also seems to have solved the odd behavior of the sidetone adjustment (where anything above 10 was earsplittingly loud; I’m now at 50-something and it’s perfectly comfortable).

So, I swapped the new antenna out for the original; still receiving well.  I’ll try to return the new one or sell it if unable…on the bright side (I guess), I now have predrilled holes for any standard antenna I might someday need to change out to…

No real forward motion on the engine issue; I did inspect the EGT connections, they seem fine.  Also pulled the prop through 12 compression strokes, and they all seemed fine at least to my uneducated hands.  It was dark and threatening rain by the time I was set to start fooling with idle adjustments, so that’ll have to wait.

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