Originally Posted by redbaron
Garmin manual says to not cut the cable but coil it. Impedence issue
Cutting it won't change the impedance, but a poor crimp/solder will increase reflections, and a shorter cable will return more of them into the unit, increasing heat load. I'll venture a wild guess that the main concern here is with the longevity and reliability of the RF output electronics, not signal integrity.
Don't cut it; coil it.
EDIT: I just realized the OP was talking about the passive GPS *input* antenna, so the above is incorrect. Still applies to other RF cables so I'll leave it here for contemplation.