[SiriusHardware]

OK, looks like both devices are amplifying their input signals, which is obviously a hopeful sign. Try some tuning. Use FM mode as it is the 'simplest' transmitter mode with the output stage running on full supply and producing constant output.

Obviously, all tuning to be done into a dummy load with a power meter in line, never into no load, and never into an aerial.

FM TX, try tuning T4 and T5 to see if they are already correctly set or whether you can make some improvement.

If adjusting them slightly clockwise or anticlockwise only reduces what little power you have, set them back exactly as you found them.