QTH.COM Swap Chat

I have an Icom 7300 which I would like to use with my Yaesu FL 2100. I purchased an Ameritron 70412 buffer/ interface to allow me to connect the two units without key voltage incompatibility. Ameritron advertises the 70412 to be the correct model but it does not work direct from the factory. After many hours of painful calls into MFJ and Ameritron they finally admitted they do not understand the directions that they sent with the 70412 , and do not know why it does not work. The directions do not mention that there are two shunt connectors inside the 70412 that will allow it to work on different radio combinations and I suspect it was shunted incorrectly at the factory. Has anyone out there figured out how to make Ameritron's product work as advertised? Or even work at all? To make the unit work what combination of shunt settings are correct? Any help would be appreciated , and Ameritron might like to know also.
Jerry
wjerry548@gmail.com
kj7ghk