This an idea that some sketch writers might want to try.
Example:
Take three lines out to a BCD to decimal chip like a 4028 and get 8 outputs - you can switch that many output filters!
2 lines = 4 out
3 lines = 8 out
4 lines = 16 out
In the uBitx there are 4 filters at the TX and that will need only two control lines from the Raduino.
Just a thought!
Cheers
--
Raj, vu2zap
Bengaluru, South India.
Raj vu2zap