Transponder problem

[fehdxl]

My buddy is having intermittent problems with his transponder in his -7A.

He's checked the connections and replaced the antenna. The shop say's it's only putting out 8W when it should be 100W. The loaner transponder acted the same way.

What other ideas are out there on things to check? Could the encoder cause these symptoms? Any other ideas?

Thanks in advance,

-Jim

[N941WR]

Jim,

Check the cable, it is possible it is either the wrong type or there is a bad connection.

[CraigC]

Cool. Long range troubleshooting. If getting partial power I would re-terminate the coax at the rack and the antenna. Also check the power and ground for full input voltage and proper ground with no resistance. Make sure the ground path return is complete and no noise or interference.

[Bryan Wood]

If you have an ohm meter try the following. With the transponder in the airplane measure the center post on your antenna to the outer ring at the base of the antenna, or to ground. You should read a dead short! Now remove your transponder and do the same test. It should read infinite. Of course do this with power off. Your going to likely find that this test will fail and you will need to change your coax, or at least a bnc connector. If you go to a shop you will pay them to do this test for you.

[fehdxl]

Thanks guys, I'll pass these ideas along and let you know what we find out -Jim

[CraigC]

Any resolution yet?

[fehdxl]

You know, not yet. I passed this info to him a last week ...haven't spoken in a bit to see what's up. I'll probably get with him this weekend so I'll ask then. Thanks for the interest. -Jim

[CraigC]

Sometimes chipping away 6 inches of ice and snow to get in the hangar is just no fun.