I just finished installing my Cobra 75 and also have an annoying high pitched whine whenever the engine is running. It goes away whenever the engine is off. When the CB is tuned to the WX channel there is no whine no matter if the engine is running or not. How's that for an interesting problem? Any ideas?

 

I found an interesting site today:

Clicky

Seems like some good ideas. I will try if my other troubleshooting doesn't work. I like the RG cable idea.

 

I may have missed it, but did you say where you mounted your antenna? I read in another thread somewhere, that with the cobra 75 handheld you should NOT mount the antenna on or near the hood or you would pick up this very problem, engine rev noise thru the cb. I am considering ordering one of the kits from cool tech with the license plate holder mount. You may be right in saying it is the cb unit itself. If it doesn't filter out the induced electrical pulses from the engine after the antenna picks them up, then that's what you would logically get. So with the antenna mounted in the rear, it avoids picking them up in the first place.

Don't know if that helps or not.

 

My Cobra 75 is installed under the glove box. I ran my power directly from the battery through the firewall. I mounted my antenna with the Cooltech bracket inside the license plate holder.

 

A couple thoughts, you can check the coax cable to make sure the center electrode is not grounded. Also take a look at the terminals you used on the ends of the power and ground wires. If you axidentally crimp the connector on the insulation of the wire or the inner part of the terminal is coroded it wont make a good contact. When you check for a ground it will appear to be good because the terminal is grounded, but the wire inside may not be. I prefer solder on connectors to the crimp on ones when possible.