George UR4CRG/RX3ARG suggests some mods to improve RX sensitivity:
- Add a parallel capacitor to R12. Try C=470 pF. George found in his signal analyser that this gave a 3 dB rise in gain at 30 MHz. He placed an 0805 SMD (or your could use a 1208 SMD part) over R12.
- Add two 100 Ohm resistors to the collectors of Q11 and Q12. You will need to cut the PCB tracks to add in the resistors. The emitter-followers do not like HF signals and a small collector resistor gives light feed back
After these modifications, reception was noticeably more sensitive/