Quick run down on the design of the IF amps and matching transformers. The radio is now a single conversion superhet configuration.
Not shown in the video was the Arduino C++ code to generate the VFO and BFO frequencies. The crystal filter has a center freq of 9.011500MHz and an assumed BW of 2.7kHz. As 80m is LSB, the VFO freq (Si5351 CLK0) was set to be 9.011500MHz + 1500Hz - Received Freq. This places the suppressed carrier of the received signal just above the passband of the crystal filter, and thus, places the LSB intelligence within the passband of the filter.
The BFO freq (Si5351 CLK2) was set to be 9.011500MHz + 1500Hz in order to mix the LSB intelligence in the product detector down to baseband (audio).
Arduino Code
si5351.set_freq(((LSB_IF_freq - freq + 1500) * 100ULL), SI5351_PLL_FIXED, SI5351_CLK0);
si5351.set_freq((LSB_BFO_freq * 100ULL), SI5351_PLL_FIXED, SI5351_CLK2);
