I am gathering parts and ideas for a BITX dual bander (20 and 40 meters). I know Farhan used a 10 MHz filter for his "Simple SSB Transceiver." But I was thinking of going a bit higher, to 11 MHz. This would allow me to run the VFO from 3.175 to 3.355 for 20 meters, and 3.695 to 3.875 for 40 meters. I'm hoping that I can do this with one single VFO (Farhan used two VFOs), perhaps with a reed relay switching in some additional capacitance for the other band. I'll also follow Farhan's lead and switch the Low-Pass and Band-Pass filters with DPDT relays.
I set up a simple spread sheet and looked at the VFO harmonics to see if any fell within the desired tuning ranges. That looks OK. I have not looked at mixing products between VFO and BFO. What do you folks think? Would the 11 MHz IF for these bands work? Or are there evil birdies lurking in my future?
I've gone ahead and bought another wood box for the new rig (I didn't even have to suffer through a second visit to the crafts store -- they are available on Amazon). I also got a roll of copper sheeting at Home Depot. This time I will prepare the box first, lining the inside with copper and preparing all the "socketry" (George Dobbs' word) before putting the PC board in.