Hi,
I have had similar issues with the A220 that have taken a very long time to track down.
I do not use the MBA-3 adapter but the symptoms seem similar in that I had perfect reception but no ability to transmit.
My avionics guy suggested the following that seems to have cured the problem.
Take ...

Do you have any Poly-Tak, Poly-Brush, Poly-Spray and Reducer.

Any quantity considered.

Please ring me at home on 0208 393 3602 or work on 0208 545 4005

Will collect if within a 75 mile radius of Epsom.[/b]

Hi Andy,

I have a hardly used PTT and lead. I don't need it now, give me a ring on 0208 545 4005 during office hours if you are interested.

Regards Alan