All modules are own developments.

The first transistor power amplifier was the HVF-1200, which could generate 1200 W with 4x VRF2933 from 1.8 MHz to 30 MHz.
This was followed by the HVF-1k2, which could generate 1200 W from 1.8 MHz to 50 MHz with a modern LDMOS. 

Both output stages were very well received and were replicated worldwide.
The Sixty One is a further development of the HVF-1k2, which continues to run absolutely stably for numerous radio amateurs worldwide to this day.

All modules are available as partial kits.
This means that all modules are pre-assembled with SMD and only a few wired components such as relays, coils, etc.
are easy to assemble.
All necessary materials are included, with a few exceptions. The scope of delivery is described in the shop.

The documentation explains the setup and also contains the measurement results, which you can of course measure yourself.
Important steps are illustrated to make DIY construction as easy as possible.