It's cool to be able to TX at a huge range of frequencies using the Fl2k dongle, but I can see (using my rtl-sdr) the harmonics are a big issue.
Can anyone suggest a good strategy for a flexible frequency (broadband) - bandpass filtering solution?
I wondered about switching in/out a range of discrete, ceramic,saw or crystal bandpass filters - a bit of a hassle to say the least.
I had also wondered if it might be possible to mix in an opposite phased signal in all but the desired frequency.
I wonder how this flexibility/broadband filtering is achieved in a analogue HF transceiver like a Icom 802?
Thanks for any ideas or input.