Here's a review from Amazon and no,I don't know how to adjust one yet
" Could Not Hear Anybody - Squelch Defective
By Lux Camper - June 9, 2010
Purchased the radio new, and installed in the same place my old radio was mounted.
My first impression was: "Wow is this thing quiet, compared to my old radio."
Well, that is because the squelch circuit was defective, and a person had to be within 100 ft of my car for me to hear them. Took it to my local CB repair shop, just to make sure it was the radio, before sending it back, and it was. The repair shop said this is not the first time they had seen this problem. Did not have anything to do with the Dynamic Squelch.
Sent the radio back and received a refund.
Never did get to run it through its paces to compare perfomance. Now I'm a bit gun-shy to try a Uniden 68 again.
What I did like, was the good sound of the speaker, and the microphone. The front panel lights and meter were not too bright at night. Overall, had the radio worked, I would have given it a high rating.
Just the luck of the draw, I received a bad one."