TDR-950

I have a TDR-950 transponder in my RV-9A. A few times the tower has told me it has been intermittent, but next time I fly it was OK. This evening, nothing. We tried ident,still nothing. Cycled Power, Nothing.

I can see that that the unit is sensing a radar sweep by the ident light flashing.

A few questions:

1)What does the TEST position on the TDR-950 do?

2) Should the antenna connector be ridgid in the back of the tray or should it have some play in it?

3) Any other suggestions?

I am going to pull the unit, clean the contacts, and check the antenna connections.

The antenna connector in the tray should "float" without the unit in place to allow alignment as the unit is inserted. But it should be secure when the unit is plugged in.

Thanks Mel

That is how it is - it kind of "floats"

This could easily be an antenna problem. It appears that the transponder is receiving a signal and trying to reply. The transponder replies with about a 250 watt pulse, and a marginal antenna connection may not be able to take this kind of power. Also the transponder may be trying to respond and the output tube is simply not functioning. First I would check all antenna connections. If they check good, then get the transponder bench checked.

Will do, Mel

I forgot to mention - the transponder was just in the shop for the Pitot Static Transponder check and they adjusted the transmitter freq and Pulse timing - then signed it off.

I had one flight after that before tonight.

I'll check the antenna and then I'll ask the shop to bench check it for me.

Thanks again, Mel

Fixed!

I found a bad connection in the coax at the antenna. Took it up in the pattern tonight and it popped right up on radar and never faded.

Got night qualed at the same time.

Mel - thanks for the help.