Cheap laser tape measure reverse engineering

I had published firmware and source code for modern B2A laser tape measure modules: 
https://github.com/iliasam/Laser_tape_reverse_engineering/wiki/B2A-laser-rangefinder-modules

I have bought cheap Chinese "X-40" laser tape. 

I disassembled it and found that it is really contains laser module that I reverse engineered earlier:

But the module version is "701A", it's not like "512A" that I bought earlier:

It can been seen that some components are placed at another places.

I want to continue reverse engineering: measure some parameters like APD voltage, desolder  some SMD components  and measure their values. It can help me to increase parameters of  laser rangefinder module.

I have tried to switch laser modulation frequency to lower frequency.

I have tested several frequencies. The lowest frequency still was working fine is 25 MHz. I found that amplitude of signal decrease to 0.65 of initial value (at 150 MHz).

I think that I need to make additional configuration of Si5351 PLL to set modulation frequency to lower frequency. My target is to set modulation frequency to 15 Mhz.

Why I need lower frequency? To increase unambiguity distance - at 15 MHz is would be 10 m.