Transponder no workie

Hottshot · Post by **Hottshot** » Tue Nov 07, 2006 9:29 am

Well any Ideas???? It does have lights but no work!!
Other than take it to a Tronicks shop.

flyer · Post by **flyer** » Tue Nov 07, 2006 4:57 pm

Hottshot

How do you know it does not work? The light is on so it has power.
Do you have a light that flashes when it is interrogated? Could it be an antenna problem?

Good Luck

flyer

Hottshot · Post by **Hottshot** » Wed Nov 08, 2006 1:50 pm

There was a hot rod that came in the last time that I was up and was goin' to fast to see me so he informed me that I needed to turn it on so I abliged him and he said I still didn't exist so either my Trans don't work or I realy wasn't there...... I am still not to sure yet...

I get no "flashy" (you know Blink.... Blink.... Blink....) light but the Insterment lights work on it so I figure it has power but from there I am not sure..

flyer · Post by **flyer** » Wed Nov 08, 2006 4:15 pm

Wup

It takes a transponder and encoder time to warm up. It may not have been warmed up. When was the last time that you know it worked?

Was this another aircraft trying to read your transponder? I would go fly and have ATC, either center or an approach control, see if they can read your transponder. I would make sure before I put money into it.

Flyer

Hottshot · Post by **Hottshot** » Wed Nov 08, 2006 4:20 pm

Flyer--

That is the plan as soon as I get weather to try it out.

as for when it worked last I don't know cuz I just got it (the plane) and it hasn't worked yet.

Kirk · Post by **Kirk** » Thu Nov 09, 2006 5:14 am

Wup,

I've become an accidental expert on transponder failure. Mines quit 3 times in 3 years.

Remember you won't get a reply light unless it is interrogated. If the "hotrod" was a turboprop or turbojet, he would have TCAS and it would interrogate your transponder. If it was something smaller and he was using a portable TPAS, it wouldn't interrogate, just monitor.

So, to get the reply light you need an ATC Radar or TCAS to whistle at it. If your airport is a long ways from any radar, you might not have a problem.

Mine is a KT76 it has a test button that should light the reply light when pressed. Try that, but unfortunately, it only tests for some internal faults. The transponder might still not work, even though the test function works. Stupid huh? All 3 times mine quit, the test button lit the light AND I got a reply light while inflight.

The KT76 gets out of alignment now and then and that is what usually happens with mine, had a transistor go bad once too. The repairs were under $250 for the transistor and $60 to $90 for re-alignment.

KT76 A or C are solid state transponders and are more reliable. Any Garmin is solid state and digital. If you have an old KT 76 like mine, I wouldn't spend more than $500 to get it fixed. It'll just crap out on you again later. A brand new Garmin installed should run about $2000 to $2500.

The KT 76 has no slide in replacements available, the KT76 A and C do have some slide in replacements available and that really helps keep your cost down.

After seeing the reliability of my 29 year old transponder, I would say, don't try to save bucks buying a used one it'll just nickel dime you forever. I've put mine on probation, next failure and that thing is out of there.

Kirk

Hottshot · Post by **Hottshot** » Thu Nov 09, 2006 6:21 am

Kirk--

I have tryed the Test butten and I still get nothin' so I am pretty sure I will end up with a new unit but I wanted to check everything before I did.

THanks

Green Hornet · Post by **Green Hornet** » Fri Nov 10, 2006 5:02 pm

Derek,
The King / Bendix are a tube technology. You can get it overhauled for @900.00 + installation , replace tube, inspect, and certify. The install should be easy since it is the same unit. My self I upgraded to a Garmin 327 since the overhaul's warranty is 90 days. The Garmin 327 is solid state warranteed for 2 years but if it last that long it should be good for 10 years. The price is 1700.00 + install that requires a slightly different rack so more time = more $$.
ADS-B is the new age avionics of the future you could wait a couple of years but once the Bendix / Kings start failing my experience is that they are repetitive failures.

Rolf · Post by **Rolf** » Mon Nov 27, 2006 5:39 pm

I had an encoder that would work sometimes but not with any regularity. Spent $200 at an avionics shop before we figured out that there was a small amount of corrosion on the top of the fuse. Scraped it clean and everything is good. Maule used automobile style fuse holders and somewhere along the line it got corroded. Transponder received fine but couldn't get enough power to transmit! The plane was a 1996 m-7
Rolf

Mr. Ed · Post by **Mr. Ed** » Fri Feb 16, 2007 3:12 pm

My xponder quit. Found the problem to be a broken fuse holder burried under the panel. Maule's auto style holders didn't hold. The ears broke off the half that screws into the other half.

Hottshot · Post by **Hottshot** » Tue Feb 20, 2007 6:41 am

I have power but it is inop so I have plans as soon as weather permits to get it fixed! Thanks for all the input guys I will let you how it turns out.