If the meter is jumping with an incoming signal then it sounds like the speaker is bad or something on the radio isn't set right. Is there a port on the back for an external speaker? If so try plugging a set of earphones in. The the squelch turned all the way down you should hear static.
What model is the CB? New or used? Is the mike plugged in? Is it new or used? Do you have a spare mic to try? Some Cobra/Uniden radios don't receive properly is the mike isn't plugged in or is bad.
What was the SWR reading you got when you set the antenna up?
I thought of this after the fact, but also agree this could be an issue. If the mic is bad, it could prevent incoming signals from being heard.. I was able to hear Dan transmit on a number of different channels, loud and clear. The antenna was set up exactly how you guys have shown in that picture, with the base of the stud grounding into the mount which grounds great to the jeep. Double checked this with a multimeter. The top of the antenna is isolated, and there is no continuity between that and ground, also double checked with the meter. The SWR on channels 1 and 40 was 1.6 after some trimming. 19 was at 1.4 . Any more trimming and the SWR would go up on channel 1, so it seems that it is at ideal point where it is now. I do believe Dan also tried an external speaker, and again, we can just hear static and nothing else. The squelch seems to work as normal, as it will shut out the static when turned up just a bit. He tried transmitting with the RF knob turned full clockwise, and full counterclockwise, and I can hear him loud and clear every time. Just no incoming signals.. This is also the same for receiving, it didn't seem to matter where the RF knob was set, he cannot hear me. He can however see the incoming signals fluctuate on his RF meter on the radio when I cue up to talk, but no sound comes through. Just static...
It all seems to point to a defective unit, which would suck! Its so stealthy how he has it installed! It would be a shame to have to take it all out again... I didn't check the continuity of the coax from the back of the cable to the front, but perhaps that would be a good step to take? However it would seem to me that the coax is good, as his transmit is crystal clear on various channels...
Install looks really good Dan, It was a pleasure to help out with it. That mount that AV. Nine made, Wow! very very slick!