Does anyone know anything about transponders?

K

kentuckynet

Guest
Hello i have a almost new Remos G-3 Light Sport aircraft...the transponder has driven me nuts since day one.
When i fly into louisville, cincinnati or lexington they cannot see me!
When i fly into nashville or my local fort campbell military base they see me and the ident works just fine.

I have taken it and had it checked ans it showed weak to the front and back...i had a new in the box microair exact replacement same make and model ...replaced it and it did the same. So all agreed it was the expensive fiberglass fin type antenna.
They did replace both ends on the cable just to rule that out.
They sold me the little stub antenna..i mounted it went to lexington........guess what same thing!!!!!!!!!!

Why can some airports see me and others not?


Theres nothing left but the cable and i cannot belive the cable is always good at home and always bad when im away. The antennas has a grounding plane and they had me take a wire from the grounding plane to the aircraft ground just to make sure as its a carbon fiber aircraft.


All microair's warranty centers just say they can send it back to australia.
This unit monitors the incoming voltage and thats not the problem......
 
I've taken the liberty of forwarding your post on to the Remos US tech guy who happens to be a friend of mine. Hope that's OK.

ps... How do you like the airplane otherwise?
 
I don't know the answer to your transponder troubles, but I hope you get it figured out. That can be frustrating.

This article has some good discussion on Transponder and antenna theory... I thought his illustration of the hallway and marbles was one of the best I'd heard when it comes to explaining SWR:

http://www.seqair.com/skunkworks/Antennas/TpxAntProbs/TpxAntProbs.html
 
Hey Kentucky, welcome to the board!

I hope you do get that figured out. I hate intermittent problems. The location issue is weird as ever. I'd love to know what is ultimately found.

I listen to JFK tower quite a bit on LiveATC.net. Several times a week, I hear a controller saying a transponder is not operating. That's not a place you want to be confused with a false return. I can't imagine it being much more comforting around CVG or the Class C's; not to mention some controllers aren't always kind to a failed transponder.
 
How high were you?

I usually fly at 700-1000 AGL and it's not unusual for me to not be seen by approach radar. I remember one time a year or so ago when me and another helicopter both got squawk codes from Allentown (PA) approach. I was to the southwest, he was to the south, we were both at 1500 MSL, and approach couldn't see either of us until we got futher east.
 
thanks for all the replies and the welcome!

The problem isnt intermittent...nashville and fort capmbell can always see me the others cannot.

My altitide is usually 3500 to 7500 feet.

My next thing i want to try is have fort campbell provide me with flight following and see what happens when they try and hand me off....should be intresting...

Ill let you know what i find as this problem has been there since day one.
 
If you could get cooperation by two separate facilities, maybe have them both look at your discrete squawk and compare returns while communicating with each other. Have each report back to you what they both see as far as type of return. That may take some sweet talking but just might help you with more data to share with the manufacturer.
 
Kentucky, welcome to this board as well. I hope the people here can help you with an answer.
 
Seems like a nice place and a good place to learn!
 
The plane came with the expensive fiberglass fin type antenna...nashville and fort campbell can see me...lou..lex..cin ..evansville cannot.

Installed the little stub antenna in a good location different from the location of the fin....same results no change from antennas or locations.

Also i switched out the micro air unit with the exact same one new out of the box...same results.

WEIRD WEIRD WEIRD
 
Find a King or Garmin to borrow for a flight or two to test.
 
It happens to lots of folks in NY airspace. I've been dropped a few times, recycled, back on. I've overheard others with the same problem numerous times. It has something to do with their radar. The first time it happened I thought "oh, great, time to replace the transponder."

The OP's problem seems to be airframe-specific.
 
kentuckynet said:
The plane came with the expensive fiberglass fin type antenna...nashville and fort campbell can see me...lou..lex..cin ..evansville cannot.

Installed the little stub antenna in a good location different from the location of the fin....same results no change from antennas or locations.

Also i switched out the micro air unit with the exact same one new out of the box...same results.

WEIRD WEIRD WEIRD
Click to expand...

Different radar sites have slightly different frequencies and sensitivities so it's not unusual for a transponder to behave differently with different sites. I strongly recommend you find a shop that can test your transponder for proper frequency, sensitivity, and output field strength with the unit in the airplane. Fixing this kind of problem by shotgunning is going to be time consuming, costly, and frustrating.
 
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