The YT-100 requires approximately a minimum of 10 watts of RF output for reliable operation. FT-817 output is 5 watts as I recall.The YT-100 manual states it may work for some users at 5 watts. That said I don't believe the auto-tune functionality is available for the FT-817 which may be the limiting factor. Also I believe the YT-100 has been discontinued, so I wouldn't expect any further development
