Tuesday, July 7, 2015

"Frog Sounds" meets si5351 meets SPAM can

I have been following Pete's (N6QW) LBS version 2 transceiver progress, and decided to put my BITX project on hold until he gets his finished.   I might just change over to some of his design instead of what I had been thinking of doing

A while ago I had purchased a small 40 Meter transceiver kit from e-bay.  This is a crystal controlled direct conversion transceiver.

Frog Sounds Radio QRP Kit Telegraph CW Transceiver Receiver Radio Station V3

I was able to listen to the streaming of some of the speakers at FDIM and one of the things mentioned was converting this transceiver from crystal control to a VFO, thought I might as well give it a try myself.
I had done a VFO using an Adafruit SI5351 break out board, and decided this would work well for this project. Looking at the schematic of the board, it uses a SA612 as a crystal oscillator, and has a simple circuit to shift the frequency when going form transmit to receive.  I will use two of the clock outputs of the si5351 instead of shifting the frequency in software when changing from R to T.  This will also make it easier to implement RIT or Split operation. 
Looking around for some Arduino CW keyer code.  I think I might be able to use some of the add on code developed for the TenTec Rebel.
I bread boarded a quick Arduino, SI5351, OLED display to see how it would work.  Most of the code from my earlier VFO ported over to use the new display with very little effort.


Looking at the size of the board, it looks like the ideal project to stick in a" SPAM" can.  Actually a " ARMOUR TREAT" can, it is much sturdier steel than the aluminum "SPAM" can. Just started laying out a circuit board for the VFO front panel, and working on adding to the software.

Will keep you informed.


  1. I will be waiting to see how you go about hooking the DDS to the frog. I am guessing pin 6 of the 612 chip?? And what to do with the open crystal sockets again guessing a jumper??
    Ron, ka2rrz@yahoo.com

  2. How did it work toi.plement a DDS?