Andrew Vine, M0GJH

Amateur radio

Recall that the amateur licence is for self-training in radio communications and is of a non-commercial nature.

Nature of amateur radio

Licensing Conditions

Types of Amateur Licence

Foundation

Intermediate

Advanced

Recall the format of the current Foundation, Intermediate and Full call signs.

Format of Amateur call signs

M3ABC

2E0ABC

M0ABC

Know the Regional Secondary Identifiers and how they are used with a Foundation licence.

D

I

M

W

J

U

Isle of Man

Northern Ireland

Scotland

Wales

Jersey

Guernsey

M3ABC becomes Mx3ABC where x = D, I, M etc

Note, there is no Regional Secondary Identifier for England

Mobile and Portable operation

/ P - e.g. MW3ABC/P

/ M - e.g M3ABC / M

A typical question

Your call sign is M3ABC. You go to the Isle of Man on holiday and want to operate from your holiday accommodation. What call sign do you use ?

MD3ABC / P

You live in Scotland and your callsign is MM3ABC. On a visit to England you want to operate with a hand held set whilst walking in the Lake district.

What call sign do you use ?

M3ABC / M

The CQ Call

CQ CQ CQ CQ CQ CQ

This is M3ABC, M3ABC calling CQ CQ CQ

This is M3ABC calling CQ and standing by

Recall the requirements for station identification.

During initial CQ Calls

At beginning and end of each period of communication

After 15 minutes

Transmission on a new frequency

By same type of transmission and on same frequency

Only send messages to other amateurs.

Some do’s and don’ts

No secret codes

No broadcasting

No transmission of music

Only the licensee personally may use the station.

Must notify Ofcom of change of address.

Ofcom local office officials have the right to close down or restrict operation.

Some do’s and don’ts

Ofcom is the independent regulator and competition authority for the UK communications industries, with responsibilities across television, radio, telecommunications and wireless communications services

The Log Book

Date

Time (UTC) of :-

first transmissionlast transmissionChanges to frequency, band, class or power

Frequency or Band

Mode

Power

The Log Book

Initial CQ Calls

Call signs of stations worked

Location when at a temporary location

Need to be able to interpret :-

The Schedule to the Licence

Band Plans

Frequency Allocation Table

Technical Basics

Identify the units of, and abbreviations for, Voltage (Potential Difference), Current, Power and Resistance.

& OhmsVolts, Amps, Watts

Note: Prefixes milli, kilo and Mega may be used.

Recall the relationship between Voltage (Potential difference), Current and Power

Power = Volts x Amps

W = V x A

Recall the relationship between Voltage (Potential difference), Current and Resistance

Volts = Amps x Resistance

V = I x R

Batteries

Polarity can be important

Direct Current / Alternating Current (DC / AC)

AC easier to generate and change voltage

Frequency

mains supply

UHF

VHF

HF

normal hearing

audio communication

50Hz (230 volts)

100Hz - 15kHz

300Hz - 3kHz

3MHz – 30MHz

30MHz – 300MHz

300MHz – 3000MHz

Frequency Allocation Table (discuss chart)

Frequency and Wavelength (discuss chart)

No need to know c = f x λ at this level

Transmitters and Receivers

1 2

3

4

Audio Stage

Modulator

Frequency Generator

RF power amplifier

frequency generation stage(s) (e.g. oscillator(s)) in a transmitter defines the frequency on which the transmitter operates.

incorrect setting of these stages can result in operation outside the amateur band and interference to other users

Need to remember

audio (or data) signal is modulated on to the radio frequency “carrier” in the modulation stage of the transmitter

FM AM

Common modulation modes :-

AM Carrier and two side bands

SSB Single side band

FM

Voice

Frequency Modulation

Morse code Carrier

Data Frequency Shift Keying (FSK) on SSB or FM

Transmitter considerations

the r.f. power amplifier output must be connected to a correctly matched antenna to work properly and that use of the wrong antenna can result in damage to the transmitter

excessive amplitude modulation causes distorted output and interference to adjacent channels

excessive frequency deviation will cause interference to adjacent channels

need to ensure that the microphone gain (where fitted) is correctly adjusted

1 2

Tuning and rf amplifier

Detection

Audio amplifier

The Receiver

3

Loudspeaker

Feeder requirements

Need to use the correct cable for r.f. signals. Coaxial cable is most widely used because of its screening properties

plugs and sockets for r.f. should be of the correct type and that the braid of coaxial cable must be correctly connected to minimise r.f. signals getting into or out of the cable.

Plugs

BNC

PL259

Antennas

the purpose of an antenna is to convert electrical signals into radio waves, and vice-versa.

¼ λ ¼ λ

½ wave dipole

λ/4 groundplane

5/8 λ

Yagi

Polarisation ?

Radiation pattern ?

Some more antennas

Long Wire

10W Gain 10 dB 100W

= erp

Effective Radiated Power (“erp”)

Gain in dB = 10Log10 (Power Out)

(Power In)

3 dB = 2 times 6 dB = 4 times 9 dB = 8 times

10 dB = 10 times

If an antenna is not correctly designed for the frequency it will not match the transmitter and will not work effectively

Points on Antennas

Where an antenna has not been designed for the particular frequency, an ATU (antenna tuning unit) makes it possible for the antenna to accept power from the transmitter.

Balanced and unbalanced

¼ λ ¼ λ

Balanced and unbalanced

¼ λ ¼ λ

Balun

Standing Wave Ratio

¼ λ¼ λ

i v

The amplitude of the standing wave varies between a minimum and maximum. The ratio of the maximum to minimum value is known as the  voltage standing wave ratio (VSWR) or standing wave ratio (SWR).

6 7 8

SWR v Frequency for a dipole 20.22m in length

A high SWR (measured at the transmitter) is an indication of a fault in the antenna or feeder (and not the transmitter

SWR

Dummy Loads

50 ohm dummy load

10 x 1W resistors

Each resistor = 500Ω

Radio propagation basics

radio waves travel in straight lines, unless diffracted or reflected.

radio waves get weaker as they spread out (inverse square law)

v.h.f. and u.h.f. hills cause “shadows” and waves get weaker when penetrating buildings but glass windows are more transparent to radio waves

Radio propagation basics

range achieved at v.h.f./u.h.f. is dependent on antenna height, a clear path and transmitter power.

Higher antennas are preferable to higher power, as they improve both transmit and receive performance.

Outdoor antennas will perform better than indoor antennas.

at v.h.f./u.h.f., range decreases as frequency increases and that in general, v.h.f./u.h.f. waves have a range not much beyond “line of sight

Ionosphere basics

70 Km

400 Km

Electrons are stripped off the gas molecules, resulting in ions, by the ultra-violet radiation of the Sun as well as incident X-rays

On h.f. almost all communication relies on the waves being reflected by the ionosphere. H.f. can provide world-wide propagation depending on how well the ionosphere bends the waves back to the earth. This varies with frequency, time of day and season.

400 Km

70 Km

Ionosphere basics

EMC Electro magnetic Compatibility

the avoidance of interference between various pieces of electronic equipment

radio transmitters can cause interference to nearby electronic and radio equipment

radio receivers can also suffer from interference from local sources

interference occurs through local radio transmissions being conveyed to the affected equipment through pick up in house wiring, TV antenna down-leads, telephone wiring etc., and (particularly at v.h.f./u.h.f.) by direct pick-up in the internal circuits of the affected equipment itself.

EMC

Chelmsford Slides

Operating practices

How to make a CQ call - HF

1) Listen

2) Check that the frequency is not being used

3) Call CQ

Operating practices

How to make a CQ call - VHF

1) Find a channel that is not being used

2) Switch to the calling channel

3) Listen and then ask if the frequency is in use

4) Call CQ

5) Having established contact switch to a vacant channel

Operating practices – need to know

Phonetic alphabet

What repeaters are about ?

Why Band Plans are used ?

Connecting anything other than the supplied microphone (e.g. packet radio, TNCs) to the transmitter requires correct operation of the PTT line and correct audio signal levels.

Phonetic Alphabet

SierraTangoUniformVictorWhiskeyXrayYankeeZulu

AlphaBravoCharlieDeltaEchoFoxtrotGolfHotelIndia

Juliet KiloLimaMikeNovemberOscarPapaQuebecRomeo

Repeaters

Output Frequency 433.300 MHz

Input Frequency 434.900 MHz

Access 1750Hz initial access

GB3GF