Trying to figure out what's wrong with my four-wheeler setup

Every item is new; Stryker 490(tuned and tested--GIJoe), mic(both stock and a new Skythumper), antenna(two but only using one--Wilson SW-2000 and/or a Predator 10K), Breedlove antenna mount. Just got a repot on I-75 today while going to the library. A very loud but clear trucker radio came back and said the modulation was above the noise but it was 'noisy', with scratchy noise in with the transmission(windows up and no AC on). He was approaching me from the rear. My first transmission was with the new Skythumper(chrome, noise-canceling model) and he said it sounded worse than the next transmission with the stock mike. I had the 10K on for this short trip. I had the RF set at just a little bit above '9 o'clock' and the mic gain at about '4 o-clock'.

Now three things are not new; the freq counter, the external speaker, and the coax. The first two should have nothing to do wit the transmissions so I deduced it must be the coax. What do y'all think is the problem?

I just ordered an 18' coax assembly(two PL-259s with heat-shrink installed) Harbour Ind. mil-spec coax.

 

Thanks Jesse. I'll try that and no, no amp and the SWR is at 1.3 across the band on the 10K.

 

Yes, it comes with talk back but I had it turned off. It comes with echo too but that was off too.