[hpsdr] duplex and alex

[alex]

Alex does support duplex as long as you leave the t/r relay on the tx 
board in tx position and then use on of the rx antennas for the rx then 
you can have both at the same time.

If you were using it for xverters then why bother with alex at all, use 
if bandpass' in the xverters and plug straight into merc and penny.

Then you dont have any unnessesary complexity or noise adding components.