1. AMATEUR RADIO TRAINING
Technical Basics
Release: v1.21
hamtrain.co.uk

2. Technical basics Units, Symbols and Circuits Conductors & Insulators
Formulas
Frequency / Wavelength

3. Units Symbol Measured in Units Voltage V Volts Current I Amps A
(Potential Difference) V
Volts
Current I
Amps A
Resistance R
Ohms 
Power P
Watts W
Frequency f
Hertz Hz
Wavelength 
Metres m

4. Large & Small Units Meaning Decimal Prefix Example milli
one thousandth
0.001 m
1mV =
0.001V 1
1 watt
kilo
one thousand
1,000 k
2000 =
2k
Mega
one million
1,000,000 M
3MHz = 3,000,000Hz

5. Electrical Symbols Cell Battery Microphone Speaker Lamp Resistor
(or bulb)
Resistor
Antenna
Earth
Switch (s.p.s.t)
Fuse

6. Conductors & Insulators
A conductor allows electrons to flow easily. An insulator does not.
Conductors:
Copper
Brass
Silver
Gold
Insulators:
Plastics
Wood
Rubber
Glass
Ceramics
Safety Note: Water is a conductor!

7. Voltage is sometimes referred to as “Potential Difference”
Direct Current
The battery provides DC Volts in a circuit
Current flows in one direction, positive-to-negative, to light the lamp
- Polarity for a filament bulb does not matter, but it does matter for other components
Voltage is sometimes referred to as “Potential Difference”

8. + - Alternating Current
AC is easier to generate and distribute AC constantly changes from positive to negative UK Mains Voltage: 230 Volts ; 50 Hz (alternates 50 times per second) + -
Time

9. P V I Power Measured in Watts (W) Power = Voltage x Current P = V x I
V = P / I
I = P / V P V I

10. Resistance R Resistors limit / oppose the flow of current
Measured in ohms Ω
In this circuit, a resistor will cause the lamp to be dimmer (low resistance), or to not light at all (high resistance) R Ω

11. V I R Ohm’s Law Voltage = Current x Resistance V = I x R I = V / R
R = V / I V I R

12. Frequency
Frequency is represented as a ‘Sine Wave’, which can be generated by an oscillator.
RF – Radio Frequency
AF – Audio Frequency

13. Frequency & Wavelength Table

14. Frequencies Mains Frequency: 50Hz Audio Frequencies (AF):
Human hearing: 100Hz to 15,000Hz
Speech bandwidth: 300Hz to 3,000Hz
Radio Frequencies (RF):
HF: 3MHz to 30MHz
VHF: 30MHz to 300MHz
UHF: 300MHz to 3,000MHz

15. Summary Symbols and Units Power Resistance Frequency vs Wavelength
Learn the symbols and prefixes (e.g: mW, kHz, M)
Recognise the symbols (resistor, cell, speaker, microphone, etc)
Power
Alternating vs Direct
Power (watts) = Volts x Current
Resistance
Ohm’s law: Volts = Current x Resistance
Frequency vs Wavelength
As Frequency rises, wavelength reduces

16. Technical basics
Any questions?
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