That is likely to be the biggest problem with RG6. I saw something about it that indicated it was not a 75 ohm setup, so you will have signal loss just by using RG6 at all, if the run is more than one or two wavelengths.
Can you get adaptors to go from RG6 connectors to the proper XM connectors? Since adaptors are made from just about everything to BCs, you might have to use two adaptors at each end. More signal losses, again mostly from mistmatching impedances.
Search the site. Someone listed the type of wire to use and also, I believe, a source of longer cables or connectors for making your own. You might simply have to give your client the choice of spending money on a short research project to find out if RG6 will work; spending that money will give him the possibility of using existing wire. If it turns out that the existing RG6 cannot be used, then he will have to go for whatever it takes to install the right wire.
Don't forget to check with Dave Houston, who does a lot of RF stuff, as to whether he has any products that could help you. I believe his member name is Dave Houston, so you should be able to find him pretty easily.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
