I have built several Avala-01’s and some home brew hybrids based on this design. The mono band design works very well and can be configured for 160, 80, 60, 40, 30, 20 meters by only changing crystal, PA LPF components and component for the recommended BPF modification. Power out should be 5 or more watts, with 20M being the lowest.
Configuring as a Multi-band radio with external oscillator brings some limitations. The IRF510 begins to lose power with an increase in spurious signals above 17M. The 74HC74 flip flop is also limited to 17M, using a 74AC74 will allow operations up to 10M. The other issue is nulling LOC using R9/10. The signal is not linear across the bands. I find it best to adjust LOC rejection on 17 or 15M, this will allow rejection >43db across all HF bands. 160M and 10M will be very close to the limits, but it is doable. Another down side the limited power on 10M, somewhere around 1W is max. The PA is limited on the higher bands. One of my modifications used the Genesis GPA10 driver circuit on the Avala. Only one hole is required to be drilled and all others fit in existing holes. It eliminates the 2N3866 and IRF510 that is replaced by 1 RD16HHF1. Power out is at least 1W and the signal is very clean. Another option is an external Amplifier that can be driven with 10mW. I have pursued several of these avenues with varying success. I will post details.