High pitch key up

Hey everyone, searched but couldn't find a good answer for my particular problem.
08 Silverado
Galaxy dx 959 wired to battery and grounded to frame
Wilson coax
K40 antenna mounted to toolbox bonded to body
Using CB speaker
SWR 1.2 on 1 to 1.5 on 40

When I turn on the radio after being off all night and key the mic it's a blaring high pitch sound comes thru the CB speaker, I can change the channel and key it and it stops or speak into the mic and it stops. Then it doesn't do it again until the radios been off awhile. And buddy says radio comes through loud and clear in his truck.
Was using SRA 198 mic just switched to Astatic 636 three days ago. Worked fine until this morning got the high pitch. Is this a mic issue?

 

Yea I had talkback pretty high and mic gain wide open. This mornin I turned the radio on and gave it a min and turned talkback down and mic gain to 3/4 and held mic up and no noise. I think it's just the mic like you're saying Wolverine. And yea I fell in love with the SRA too that's why I got it in my big truck. Sounds a lot better than the Astatic people say.
Preciate all the input

 

Yea I know right? I just recently got the Ranger when it came with the General Lee and was kinda iffy about it at first even after hearing good things about it. But I love it now, it works and sounds much better. And feels like it could take more abuse than the light weight Astatic. And like I said only reason I changed was to keep the Ranger in my big truck. Don't use the pick-up CB to much. Fairly new to the side-band side of things and do more listening than talking, lol