My first Duplexer from BuyTwoWay covered the entire GMRS Band and my repeater then was on Ch 22. I had a terrible experience with it, ended up buying a tuned dublexer tuned for Ch 18 and moved there.. Been working great since.. I sent the original duplexer back to BuyTwoWay and had them tune for CH 18 to use for my portable repeater which i mounted to the outside of a FAT 50 Ammo Can. Since this portable set up gets moved around a lot, i'm always concerned that the duplexer will get knocked off tune, but going to almost 3 years now its holding tight on Ch 18.. I did try to tune it myself as Marc did, but didn't have such luck or patience.