I’d like to add an aftermarket antenna to my cobra HH50wxst to boost my range. My only concern is if I got a longer antenna, could it possibly throw off the SWR and damage the radio? I am totally new to this hobby and am afraid to break things. Any advice on this matter would be greatly appreciated.
If you are going to buy an antenna designed for use with that handheld, then it should work fine. Otherwise, you need to make sure that you get an antenna designed for the frequencies used by the radio (in this case around 27MHz, or 11-metre band), that has an impedance of 50 ohms, and has a BNC plug on it.
As long as the antenna meets those criteria, it should perform at least as well as the included antenna. For best results, an externally-mounted antenna is recommended if you will be operating from home or from within a vehicle. This is because signals will be attenuated by the walls or your house, or by the body of a car or truck.
This is the case for all radios, including but not limited to: CB, amateur, commercial, government, or emergency services.