ADS-B / transponder problem??

[Jimbo97]

I had an interesting occurrence on my bay area tour over the weekend. I dialed in my transponder code as directed. NorCal then asked if I had 2 transponders on board. I didn't of course but they were seeing 2 codes from my plane. Reset the transponder twice to no avail. I then tried unplugging my new portable ADS-B and the second set of numbers they were seeing disappeared. It was the first flight with it. Contacted the manufacturer of the ADS-B and they said to try moving it to the other side of the dash, or try removing the wifi antenna from the unit.

Haven't been able to fly again yet to test either remedy. Anyone have any ideas on this. Seems it shouldn't interfere with a transponder any way as its meant to be right there in the cockpit. I have a Narco AT-15OR transponder. Head scratcher!

Thanks!!

 

[Brad Z]

What do you mean by portable ADS-B? In or Out? If it's ADS-B In, it shouldn't effect things at all; it's a receiver.

Is it possible your transponder was flipping back and forth between two codes? Sometimes the dials will get misaligned and a digit will flip back and forth, appearing as two transponders squawking two different codes on the controller's scope, depending on what code is transmitting when the radar sweeps you.

 

[Jimbo97]

It's a portable dual channel ADS-B. It plugs into a power outlet. I understand it's a receiver but as I said, when I unplugged it the problem went away which means it's not sticky knobs. The 2 codes were not even close, btw

 

[Brad Z]

It's a portable dual channel ADS-B. It plugs into a power outlet. I understand it's a receiver but as I said, when I unplugged it the problem went away which means it's not sticky knobs. The 2 codes were not even close, btw

The ads-b receiver is a red herring. I suspect it has nothing to do with the issue.

Did the problem return when you plugged it back in?

What were the two codes?

 

[Jimbo97]

The problem did return. Don't remember specifically the codes, but input code was 5344 and second code they were seeing was something like 5577

 

[Brad Z]

The problem did return. Don't remember specifically the codes, but input code was 5344 and second code they were seeing was something like 5577

It might also be worthwhile to see if the problem exists when interrogated by another radar facility, i.e. another sector or another Tracon, Center, etc.

I still suspect the transponder needs some internal adjustment.

 

[Jimbo97]

Thanks for your thoughts, Brad... I am going up today to do some testing at different altitudes to see if they are still seeing 2 codes.. It will be with another center, as you suggested. Will try in both ALT and ON modes of the transponder as well, and will record the codes. ALso, the power plug was inadvertently put on the avionics switch... going to have our shop change that after I land, then try the above again on the way back to home airport...

 

[flyingron]

Back in the old turn-the-dials transponder I had a flako one in the rental that or'd 41 octal in with all the codes. We diagnosed this by having ATC read me back what he was seeing as I tried various settings on my end.

 

[Jimbo97]

Well....went up today, semi hoping we had the same problem so we could do some diagnosis, but NorCal said they only saw one transponder code today, so some of the general thinking is that it was the software in the Bay Area's region.. well, here's to hoping it is a problem of the past