hmmm, pretty technical. But with all due respect to those with electronics experience, I think this is a bit much. For a stock CB with no amplifier, I would run the power lead directly to the battery to help reduce any noise that may be present if connected to the fuse block (alternator whine, windshield wiper motor noise, etc). Use the standard old 3amp or so fuse that came with the radio. Run a ground wire to a good ground and go.
Different story with an amplifier, but for an over the counter CB, nothing elaborate is needed.

 

Sorry Matt I did not intend it to come out like a personal attack. My apologies. I find this forum to be very valuable for an exchange of information.

J15Big, you only need a fuse in the red line. The value is determined by the CB manufacturer. You could ask a Radio Shack sales person if you no longer have the manual for your CB or you could compare similar models. If you use one that is too big you will burn out the CB instead. There is no cathode or anode description used for the power wires. Red is positive, black is negative which in an automobile is also chassis ground. The reason you never fuse your ground is safety. If the fuse blows you will still have potential voltage in the device. In a car it is only 12 volts and you will not really get hurt but in your house it is 120 Volts which could kill you. This is the same reason why the light switch in your wall disconnects the Hot line and not the neutral line. If you switched the neutral and changed a light bulb the socket would still be live. This could shock you if you touched it because you would complete the circuit path.

Linetest is correct in saying that nothing elaborate is needed and a 3 amp fuse may be close to what the CB actually needs. He is incorrect about the noise issue. If you have noise at your fuse block you will also have noise at your battery. After all they are physically connected to each other by a large positive wire. If your stereo does not have any noise issues your CB should not. Proper grounding will help with noise problems as well, not every bolt under your dash is actually grounded. Look for one that has other black wires from other devices and add the CB black wire to it. Some CBs are worse than others at picking up noise and that has to do with the isolation built into the power supplies. The cheaper the CB the more likely you will have noise problems.

 

Norm, we agree to disagree.
J15BIG, lets just say that if you experience any whine or static that is produced after the car is started or switched to the ACC position, the try running running the power lead to the battery to see if the noise is reduced and/or eliminated.
Norm, you will be the first one I've ever met that said running a power lead to the battery is no different than the fuse block. The battery is more isolated than that, especially when it comes to electrical interference on an RF device.
But, a debate will not serve anyone. So, J15BIG, keep it simple, and try the power lead both ways if you like and see if there is any difference for you.

 

Ok we can agree to disagree. The alternator is connected directly to the battery so if it was making noise you would get it there as well. With audio amplifiers we run a wire to the battery because we need more current than the fuse block can support. I did not say there was no difference only that noise was not one of them. Wiper motor noise is dependent on proximity to cabling. RFI is removed by most power supplies which is as I said in the above post. The cheaper the device the more likely you will have noise because they are less likely to install filters or isolation devices. Even a simple ferrite core on the power wire can get rid of some RFI but when a company mass produces a product (like CBs) profit margin is the key, the bigger the better and CBs are so noisy anyway that most users would not be able to hear alternator whine over the background noise of the CB itself so manufacturers cut corners. If that is a problem for the consumer they would purchase a higher end unit with better isolation and noise suppression.