Radio

•The Foundation Licence is the first of three UK levels: Foundation, Intermediate and Full

Dates back over 100 years

The London Wireless Club, now the RSGB launched over one hundred years ago

Amateurs were heavily involved with reception of enemy messages in World War II

Originally used Morse code, followed by voice

Used to save lives in the 1953 floods

Played an important part in the 1982 Falklands War

• Broadcast radio and TV         
• Mobile phones
• Emergency services
• Military
• Aviation
• Maritime
• Space exploration
• Businesses / Taxis
• Satellites / GPS
• Wi-fi and Bluetooth
• Baby monitors
• Cordless phones
• CCTV / Security systems
• PMR / Walkie-talkies

HF:   3MHz to 30MHz

VHF:   30MHz to 300MHz

UHF:   300MHz to 3000MHz

• Amateurs have several frequency bands that we are allowed to use
• The table is published in “Foundation Licence Now” (and with the exam)
• Some frequencies are shared with “primary users”
• We cannot cause interference with other services

•Amateurs refer to bands by frequencies and wavelength
•A VHF frequency of 145MHz has a wavelength of 2 metres

HF:        7MHz = 40m    

 14MHz = 20m   

VHF:  

145MHz = 2m

UHF:        430MHz = 70cms

•Block Diagrams •Modulation Types •Station Setup

A radio transmitter has four basic stages:

• 1. Audio Stage
• Gets and amplifies weak signals from the microphone
• 2. Frequency Generator
• Creates the radio signal on the right frequency
• 3. Modulator
• Mixes the radio and audio signals together
• 4. RF Power Amplifier 
• Increases the combined signal and feeds to the antenna

1: Audio Stage

2: Modulator (More on this shortly)

3: Frequency Generator (also referred to as an Oscillator)

4: RF Power Amplifier 

A radio receiver has three basic stages:

1. Tuning / RF Amplifier

Tunes into the required frequency

Amplifies the weak signal so that it can be used

2. Detector

Extracts the audio from the radio signal. Often called “demodulation”

There are different types of detector for each modulation type

3. Audio Amplifier

Amplifies the audio and feeds it to a loudspeaker or headphones

1: Tuning and RF Amplifier

2: Detector (also referred to as a “De-modulator”)

3: Audio Amplifier

Audio signal

Carrier

Modulated signal

Audio Signal

Carrier

Modulated signal

CW: Tones generated using a Morse key

Data: Audio tones generated via a computer soundcard or a TNC (Terminal Node Controller)

CW Audio

CW Signal

At Foundation, you can only use commercially-purchased transmitters (no construction)

You must only transmit on allocated frequencies and must not exceed permitted power levels 

‘Over-modulating’ or ‘Over-deviating’ may result in interference to other channels as well as poor audio quality. Take care with audio levels (microphone gain, shouting, data signals from a computer)

You must stay in-band, not cause interference, and test your transmitters “from time to time”.

Microphone

Power Supply

Transceiver (transmitter & receiver)

SWR Meter

RF Filter

ATU

Antenna

High voltage carries a risk of electrocution

High current carries a risk of overheating and fire

Take care with mains-powered equipment (230V AC)

Switch off and unplug equipment before working on it

Take care with batteries and avoid short circuits. Even a low voltage battery can overheat and cause a fire.

Electrocution: Disconnect the power immediately. Ensure power off before touching victim. Summon medical help

Brown: Live

Blue: Neutral

Yellow/Green: Earth

Plug / cable undamaged

Correct value fuse (P = V x I)

Avoid whiskers

Flex secured

Earth connections prevent metalwork becoming ‘live’ in fault conditions

Don’t mix the mains earth with the RF earth

‘PME’ - Protective Multiple Earthing 

Be aware of “PME”. Some homes use this – the neutral and earth are connected. Out-of-scope for this course, but be aware of the term.

Can be very nasty, and the effects are not always felt immediately

Do not touch antenna whilst transmitting

Insulated wires, such as antenna and feeder cable, can still give an RF burn

Be careful when wearing watches, rings, etc. near RF

Ensure your shack has a single, clearly-marked ‘OFF’ switch

Exercise care when using and storing tools

Take care when using headphones – loud noise can damage your hearing. Damage can be cumulative

Trailing wires are a trip hazard

Avoid liquids near equipment

Avoid overhead cables and phone lines

Secure antennas and feeder safely, insuring no accidental contact

Care when using a ladder (ladder secured,wear a hard hat)

At least one adult must be present

Risk of lightning strike on high antennas

Do not touch an antenna whilst transmitting 

Car batteries: 

High current, danger of overheating, corrosive acid

Risk of tripping over cables

Risk of overhead wires

In-car: Unsecured equipment; distractions ; use hands-free equipment