I know this is an old thread but I just used this TX/RX pair in a non-los install so I thought an update appropriate. I needed a wireless sensor 600’ from my home and other 433mhz radios could not handle the terrain. The receiver is mounted on a 6’ pole but the transmitter is about 5’ below grade. Said differently I would need to raise the Tx about 5’ to achieve los with between the two components, not including fir trees and shrubs. Even without los the system is working very well. Remember these radios send only 4bits (of user data) each packet so this is not a high speed link but excellent for a low bandwidth sensor network.