Power supplies.

Types.
There are two main types of power supply, the standard linear and switched mode types. The linear regulated types can be either series or shunt regulated.
Switched mode power supplies are more efficient and run cooler but, as they run at high frequencies, they may radiate RF signals that can interfere with radio equipment.

Legal requirements.
As the supply connects to the mains supply, there will be legal and safety issues associated with such devices.
If working on any device that plugs into the mains supply, it is recommended that you read up on the legal and safety requirements at your location. Failure to follow safety or legal requirements may result in death.

Radio requirements.
A standard, legal mobile UK CB radio requires a voltage of between around 11.4 to 14.2 volts and a current of up to 2 Amps. The voltage should be smoothed and regulated - it should not have too much ripple and should not drift when the current used changes.
If it does not meet the requirements the CB radio may make humming noises or, even worse, the radio and the supply may be permanently damaged.

Ideal supply.
For equipment to last, it should not be run at its limits. Running at the limit will cause damage over time. The ideal supply will be capable of delivering slightly more current than is required by all the equipment which will be connected to it.
For a standard, legal UK CB radio, this would be around 13,5 volts and 3 Amps.

Further information.
  Linear supplies.
  Switched mode supplies.
  Regulation.