481THz line of sight

For the uninitiated, 481THz is red light. 

My main interest in lightbeam communication was over the horizon beaconing (NLOS), but I did have one speech QSO line-of-sight over about 11km. As mentioned before, all my optical gear was homemade in the back of the garage. Most of the test gear was also homemade. In fact, optical gear is easier than microwaves and there are plenty of sources of ideas on the internet. My own page may trigger some ideas. The circuit above was used in the speech QSO.

See https://sites.google.com/view/g3xbm4/home/optical-nanowaves/line-of-sight .