This is a small adapter board to use an HC-05 or HC-06 bluetooth serial adapter for a Yaesu FT-100, FT-857, or FT-897. The circuit is exactly the same as the one for the FT-817, just a slightly different mounting method for the LED and Mini-DIN 8 connector. SJ1 is used to provide V+ to the adapter to enable AT command mode on an HC-05. R1-R3 are identical values, and are used to convert the 5v TTL signal from the rig to the 3.3v signal expected by the bluetooth adapter. R4 is the current limiting resistor for using an HC-06, R5 is the current limiting resistor for the status LED for an HC-05. R4/R5 may be omited if you do not desire having a status LED. The voltage regulator is a AMS1117-3.3v or LM1117 3.3v regulator. This board is designed to go straight off the back of the radio and not interfere with any other ports. This board WILL NOT fit on the FT-817 when it is standing on it’s back feet, although otherwise it will work.