xponder problems

Wxman2000 · February 3rd, 2008, 02:17

OK, so I've been having a few problems with the xponder in my plane and was wondering if anyone might have a few ideas what the problem may be with it.

Sometimes, it works great, no problems through the flight. Other times, ATC is unable to pick up anything from it, though I'm still getting a reply light in the plane. And even other times, it seems to be hit and miss through the flight with ATC seeing it, sometimes not at all, sometimes what they describe as "very weak". All the while in all these cases, I'm continuously getting a reply light on the unit itself.

Any ideas what may be the problem? I was wondering if maybe it was the antenna or something since it seems to be working fine by how it acts in the plane. Any help would be much appreciated. Thanks.

ZachH · February 3rd, 2008, 02:19

No idea, But good luck !

Sidious · February 3rd, 2008, 09:19

It could be the antenna, I remember hearing that one of our training aircraft was having a similar problem last summer and it was just that. Have you have anyone look at it?

bustinminimums · February 3rd, 2008, 11:41

As some of the others said earlier check your transponder antenna and the connections to it. If that does not solve it then you might have something internal with the the transponder like a power problem that is intermittent which can cause the same thing.

fadec · February 5th, 2008, 11:40

Ditto checking the connections, but if you don't see anything obvious immediately take it to a shop with the proper test equipment.

While I don't wrench in the general aviation world, I can't tell you how many times and thousands of dollars in parts that I've seen wasted in the commercial environment (control heads, lru's, antennas) when the problem was the cable.

Very common problem on aircraft coming out of overhaul. Especially the Guadalajara specials.

ElyJs · February 22nd, 2008, 02:19

Its either the encoder or the transponder itself. Go to a local avionics shop and have them test it on the ground with their computers. Best bet is to convince them to give you a loaner transponder to see if that fixes the problem. Most can be swapped out in less than 5 minutes. If it doesn't its probably the encoder (or antennas/connections). I call this guy that works out of a van. Usually if its working part time he will pull it apart and fix it. I would not pay more than $450 to get this fixed.

I have played with his handheld tester that gives an incredible amount of information. Something about the wavelengths being set properly could lead to a weak signal. If it is working part time you probably don't need to buy a new $1300 transponder.

This is all from my transponder problems with my plane, I don't really have a great grasp on any of it, just throwing out some ideas.

-Jason

Stonefly · February 22nd, 2008, 12:05

Quote:

Originally Posted by Wxman2000

OK, so I've been having a few problems with the xponder in my plane and was wondering if anyone might have a few ideas what the problem may be with it.

Sometimes, it works great, no problems through the flight. Other times, ATC is unable to pick up anything from it, though I'm still getting a reply light in the plane. And even other times, it seems to be hit and miss through the flight with ATC seeing it, sometimes not at all, sometimes what they describe as "very weak". All the while in all these cases, I'm continuously getting a reply light on the unit itself.

Any ideas what may be the problem? I was wondering if maybe it was the antenna or something since it seems to be working fine by how it acts in the plane. Any help would be much appreciated. Thanks.

How old is the avionics in your airplane? Older resistors, transistors, capacitors and the like can degrade over time. They are susceptible to heat and vibration. In this day and age of disposable electronics (not necessarily avionics) people don't tend to repair electronics anymore. How many television repair places do you see anymore? However, with the cost of avionics, people rightly so continue to use older equipment. However, older avionics are, as I mentioned, susceptible to degradation.

Wxman2000 · February 22nd, 2008, 19:37

Well, I've ordered a new antenna and connections to see if any of that might fix the problem. At best, it may turn out to be the cheapest thing that is wrong, so I'll go that route first.

The equipment isn't very old, the encoder was installed in 2004, and the transponder (narco at-150) was installed in either the late 90's or early 00's, can't remember right off hand.

SIUav8er · February 26th, 2008, 02:54

Good old avionics problems. Theyre a bitch to troubleshoot sometimes, especially if the problem is "intemitant"

February 3rd, 2008, 02:17	#1
Wxman2000 Newbie Join Date: Mar 2007 Posts: 21	xponder problems OK, so I've been having a few problems with the xponder in my plane and was wondering if anyone might have a few ideas what the problem may be with it. Sometimes, it works great, no problems through the flight. Other times, ATC is unable to pick up anything from it, though I'm still getting a reply light in the plane. And even other times, it seems to be hit and miss through the flight with ATC seeing it, sometimes not at all, sometimes what they describe as "very weak". All the while in all these cases, I'm continuously getting a reply light on the unit itself. Any ideas what may be the problem? I was wondering if maybe it was the antenna or something since it seems to be working fine by how it acts in the plane. Any help would be much appreciated. Thanks. __________________ Aaron PP-ASEL IA There are three simple rules for making a smooth landing. Unfortunately no one knows what they are.

February 3rd, 2008, 02:19	#2
ZachH Junior Member Join Date: Nov 2007 Location: Fayetteville Posts: 279	Re: xponder problems No idea, But good luck ! __________________ If guns kill people I can blame misspelled words on my pencil - Larry the Cable Guy.

February 3rd, 2008, 09:19	#3
Sidious Senior Member Join Date: Oct 2006 Location: Titusville Posts: 345	Re: xponder problems It could be the antenna, I remember hearing that one of our training aircraft was having a similar problem last summer and it was just that. Have you have anyone look at it?

February 3rd, 2008, 11:41	#4
bustinminimums Newbie Join Date: Oct 2007 Location: Juneau Posts: 27	Re: xponder problems As some of the others said earlier check your transponder antenna and the connections to it. If that does not solve it then you might have something internal with the the transponder like a power problem that is intermittent which can cause the same thing.

February 5th, 2008, 11:40	#5
fadec Junior Member Join Date: Oct 2007 Location: North of ATL Posts: 32	Re: xponder problems Ditto checking the connections, but if you don't see anything obvious immediately take it to a shop with the proper test equipment. While I don't wrench in the general aviation world, I can't tell you how many times and thousands of dollars in parts that I've seen wasted in the commercial environment (control heads, lru's, antennas) when the problem was the cable. Very common problem on aircraft coming out of overhaul. Especially the Guadalajara specials.

February 22nd, 2008, 02:19	#6
ElyJs Junior Member Join Date: Jul 2006 Location: Boulder, Colorado Posts: 269	Re: xponder problems Its either the encoder or the transponder itself. Go to a local avionics shop and have them test it on the ground with their computers. Best bet is to convince them to give you a loaner transponder to see if that fixes the problem. Most can be swapped out in less than 5 minutes. If it doesn't its probably the encoder (or antennas/connections). I call this guy that works out of a van. Usually if its working part time he will pull it apart and fix it. I would not pay more than $450 to get this fixed. I have played with his handheld tester that gives an incredible amount of information. Something about the wavelengths being set properly could lead to a weak signal. If it is working part time you probably don't need to buy a new $1300 transponder. This is all from my transponder problems with my plane, I don't really have a great grasp on any of it, just throwing out some ideas. -Jason

February 22nd, 2008, 19:37	#8
Wxman2000 Newbie Join Date: Mar 2007 Posts: 21	Re: xponder problems Well, I've ordered a new antenna and connections to see if any of that might fix the problem. At best, it may turn out to be the cheapest thing that is wrong, so I'll go that route first. The equipment isn't very old, the encoder was installed in 2004, and the transponder (narco at-150) was installed in either the late 90's or early 00's, can't remember right off hand. __________________ Aaron PP-ASEL IA There are three simple rules for making a smooth landing. Unfortunately no one knows what they are.

February 26th, 2008, 02:54	#9
SIUav8er Senior Member Join Date: May 2005 Location: at work Posts: 909	Re: xponder problems Good old avionics problems. Theyre a bitch to troubleshoot sometimes, especially if the problem is "intemitant" __________________ Commercial Pilot, CE-500 Gold Seal CFI.II.MEI IGI Future GoJet Pilot.

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