Hello all. I recently got a psr-600 and my question is about the squelch. On all my other scanners when you rotate the squelch all the way counter clockwise it opens the squelch and you hear static. However the squelch on the psr-600 seeems to have no effect. rotating it all the way to either side seems to have no effect on the signal and doesn't open and have static. Is this proper operation for this radio? Thanks.