SO WHAT'S IN YOUR RADIO?
Here is a listing of individual circuits that you must be familiar with on the exams. Below the list, you will find block diagrams of practical radio circuits. Each test potentially will have at least one question on the exam pertaining to them. On the exam, a diagram will have a missing block label, and you will be asked to fill in the blank OR if given a label, be able to name the component. Currently, there is enough information here to be able to answer the test questions. I hope to have a better description of their functions soon.
Marker Generators: A high-stability oscillator that generates reference signals at exact frequency intervals; used to calibrate the tuning dial on a receiver.
Crystal Calibrators: Used to inject a frequency calibration signal into a receiver.
Signal Generator: Produces a stable, low-level signal that can be set to a desired frequency; it is used to align tuned circuits.
Variable Frequency Transmitter: Consists of a variable-frequency oscillator connected to a driver and a power amplifier.
Detector Circuit: Combines signals from an IF amplifier stage and a beat-frequency oscillator.
FM Receiver: A circuit that uses a limiter and a frequency discriminator to produce an audio signal.
Oscillator Circuits: Used to control the transmitter frequency.
Detector: Combines the IF and the beat frequency oscillator.
A QUICK NOTE ON RADIO POWER WIRING
When wiring the power to your radio, you may end up with a slew of wires. In three-wire AC power supply applications, GREEN is a ground that should be connected somewhere to the chassis. The chassises of all of your individual radio components should be connected together to properly ground them. BLACK or RED is the hot (live) wire; it should be in line with a fuse to prevent circuit burn-ups. The WHITE wire leads to the neutral side of the power transformer's primary winding. When installing a wall outlet, you will find that the terminal screws are color coded to indicate polarity.
When installing your mobile unit, you will generally find both red and black wires leading from your radio to your battery. The red is the ho wire and the black is the ground. Fuses should be placed in line with both of these wires.
NOVICE LICENSE EXAM DIAGRAMS
TECHNICIAN LICENSE EXAM DIAGRAMS