New draw length require new string?
 

I've got to change the cam on my new used Switchback XT to get the 30" draw that I need. Will changing from a 28" to a 30" draw require a new cable and string?

If your bow has the capability of changing draw length (as most do these days) NO you do not need a new cable and string. The design of the cam modules allow the string to roll over the cams a specific amount which alters the draw length. Putting on a longer (or shorter) string or cable will change the bow's axle to axle distance which would take the bow out of spec and possibly be dangerous.

On a switchback, I believe you have to change the whole cam to change draw lengths. I know that on some hoyts that would require new strings and cables when jumping a couple of inches but I do not think you have to on a switchback. Cams are pricey if buying from a dealer.

All the more reason to not buy a bow that is draw length specific unless you know going in that a cam swap is going to be needed.

The Switchback XT draw length can be adjusted by just swapping cams to the desired size. The same string and cable will be used for all draw length cams.