your problem is you are lost in the land of half duplex transceivers. The flex radio is a full duplex radio. With the added receiver you have three independent processes going on all the time. In fact with the extra receiver you could receive on 20, receive on 15 and transmit on 40 simultaneously. No switching. On 20 you could transmit and receive simultaneously or on 15 you could receive and transmit simultaneously.
First in my experience there is no need for bandpass filters. I use my 2 SDR-1000's at 1500W on 2 bands every day The antenna are 100ft or less apart and I have no desense on the non transmitting band. Using a DSP based radio, as long as the AD/DA channel doesn't overload the filters are 100% effective. Second you need 2 complete signal paths from antenna through amp to the radio. If you want a 20 and 15 setup from the back of the radio you need a 20M amp connected to ant 1 and a 15M amp connected to ant 2 and the amps connected to their respective antenna and key lines. Then it is merely a matter of listening on 2 bands and aiming your transmitter to what ever band you want to transmit on, just the same as any SO2R. The audio duties can be handled in software with as many right ear, left ear, both ear, side tone, combinations as you want. Side tone is just another digital process to be route. PowerSDR already has the algorithm for panning 2 receive channels across the stereo spectrum. Given the switching times you could transmit alternate words on alternate bands at 1500W all the time while listening to both bands. If you need to use the same antenna for transmit and receive a PIN switch will solve that. I use PIN switches at 1500W all the time. Full duplex with three running processes and software control of routing the audio as a digital entity, and control signals generated in software is the key and it is why the flex is such an innovation. 73 W9OY __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ FlexRadio mailing list FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Knowledge Base: http://kb.flex-radio.com/ FlexRadio Homepage: http://www.flex-radio.com/
