SSB6.1 RTX with band switching

I made some progress with the SSB6.1 radio.  I wound and added the two 40 meter coils and two of the plastic connectors.  I decided it would be easier to use Female-Male jumpers instead of continuing to tack-solder Male-Male jumpers to the PCB.  It turns out that my tack-soldering was a bit more substantial than I had hoped -- one connection required a lot of solder wick to clean and I manged to lift the PCB foil.  Oops!  Well, stuff happens...  I wired up a small jumper on the bottom of the connector and I'll run it directly to the opto-isolator input pin...

I decided to split the radio control from the user interface.  The radio control will use an Arduino Pro Mini while the user interface can vary as desired.  The connection between the two will be via a TTL serial port possibly using RS-485.  This will allow me to have a sealed RF deck and have a remote user interface.

The SSB6.1 has 6 input pins used to select the band.  I wired up a 74hc295 (a 3 to 8 demultiplexor / decoder) to control the band selection.  This chip has 3 digital inputs (binary 0 to 7) and will assert 1 of 8 outputs.  In this application, this will allow only one band to be active at a time.  Fortunately I had a couple in my parts bin (any guesses as to how long?).  It's been sitting in the package for a while but it still works!

There are 4 other inputs to the SSB6.1.  Two are used to select the sideband and two are used to allow SSB or CW transmit keying.  One is labeled as 'CW' and the other is mysteriously labeled 'DT' (on the schematic, this is the DDSPTT input for SSB keying).  I am currently using a couple of digital output pins on the Arduino to select either upper or lower sideband. It's simple and I have a few pins on the Arduino.

On a whim, I threw some $$ at a kickstarter campaign for a fun speech chip that I may use to provide voice feedback.   There is even a version of the chip with words centered around communications (like phonetics).  It should be interesting to play with.

From top left clockwise:  the voice chip, the Arduino Pro Mini with the 74hc295 below it, the SSB6.1, the Si5351 DDS, and finally my trusty old Radio Shack digital logic probe.

With the band and mode selection and a serial connection to the PC in place, I can set the frequency, the band filter, and the mode via keyboard commands.  And, 40 meters sounds great!  :-)