"That is a beautiful Yagi, or is it a beam since your RX is on HF? Looks like a Yagi."
Yes. The log-periodic is a beam, and a type of yagi. They generally are useful where you are wanting a directional array that works well over a wide range of frequencies. Larger versions of Dave's array were widely used by the military back in the days before the Internet, satellite communications, and cell phones.
The antenna above the log-periodic appears to be a 50 MHz yagi and the smaller one at the very top of the tower 146 MHz. Nice setup!