Kinda-sorta back, I am recovering from cataract surgery. Yes the vinyl tip cover has a capacitive effect on the antenna which simply means it slightly detunes the antenna by changing its resonant frequency. It's normal.Ive noticed that when I put the firestik "cap" back on it throws my SWR all over the place. Could this be an indicator that I need a longer antenna such as a 3' instead of this 2'
Not sure. I have a 3’ one and my SWR is around 1.5 and i just have a CB. My GMRS radio is a handheld. Hope @Jerry Bransford is back and can educate us on that part, He is a communication expert.
You get around that issue by slightly detuning the antenna in the direction where when replacing the vinyl cover it moves it back where you want it so the SWR is low or at least lower. It's a trial and error procedure. Detune it with the tuning screw off to the side of the lowest SWR and see if replacing the cover makes the SWR better or worse. If it makes it worse, tune the antenna to the 'other side' of the lowest possible SWR and see if reinstalling the cap moves the SWR lower as it should. Doing this a couple times should give you a good low sub-2 SWR. Yes I hate the effect that vinyl tip cover causes too lol.