Can two ATC Transponders use the same antenna?

Question

I am adding in a second Transponder and was wondering if it will need its own antenna or if I can splice off the original

Answer 1

Yes, you could use one antenna, because you would only use one transponder at a time while in flight. Use a "T" fitting to join the coax cables.

Answer 2

It depends...

Steve-O is right, but at the same time, as mentioned also, you can put in two to the one antenna but can only use one at a time.

So in that case, you'd use the most advanced - say, Mode S over Mode C.

It depends, too - are you using transponder to mean exactly that?

Or to refer to SSR equipment in general?

Because if it is ADS-B equipment, don't quote me but it would most likely be a bit different...

Answer 3

I assume you have an A&P. It should have its own antenna because the wire from the antenna is probably coaxial and would be a ***** to splice. Also, who knows how the two units might interfere with eachother. Put in a second antenna, cheap insurance.

Answer 4

The best answer would be to contact the manufacturer of both units and see what they recomend.

I have a hunch their answer will be similar to what Steve-o said.