开云体育

Adrian,

The si5351 on the Raduino drives that "DDS1" cable from a CMOS driver through a series DC blocking cap.
Should see about 3v pk-pk there when you unplug the cable.
Your 20-30mv seems low to me going into Q9, but probably just fine if you are seeing 1.5v pk-pk out of Q7.

The board was originally laid out for an analog VFO at Q9,
C91 and C92 (also L7) should be removed if driving the VFO from the Raduino.
Also,? C103 in the BFO is not stuffed, L5 is shorted across for 0 uH,
with matched 12mhz crystals the BFO winds up reasonably placed with respect to the crystal filter.

Signal levels in the RF and IF sections are kept quite low.
I'd assume on the order of 0 dBm max into the demodulator at D15,D16 (now stuffed with a single BAT54S, no pot at R106).
The three bidirectional amps are probably on the order of 15 dB of gain, the first mixer and demodulator lose around 6dB?
Crystal filter and LPF at L1,2,3 might each lose on the order of 3dB?
Most of the gain is in the rx audio preamp and audio power amp, around 40dB each?

There are listings somewhere in this forum for DC voltages at all those transistor pins,
but basically you want to verify that emitter quiescent is above ground, base is 0.6v above that
on all the active parts (rx side of the bidi amps!) when receiving.

I'd recommend debugging with the original firmware if that Raduino has it loaded,
perhaps yours is loaded with uBitx firmware instead (which won't work at all)?
If you do need to recompile, then use Allard's Bitx40 firmware, no mods required:
? ??
Eventually, you might want to move up to Allard's v2 firmware:
? ??
Allard's v2 firmware gives a lot more features, but does require a few hardware mods.
Both have the si5351 routines included inline with the main body of code, no libraries.

Good Luck!

Jerry, KE7ER