Transcript
V: Velocity of E M waves in free space is 3 x 10 8 m/s (300,000,000 m/s)
Frequency and Wavelength
v m/s
V=fx f = V/
f hertz
metres
= V/f
Power
P watts
P=VxI V = P/I I = P/I
v volts
I amps
Ohms Law V=I xR
v volts
I = V/R R = V/I
I amps
R ohms
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Series
Req = R1 + R2 + R3 …
Parallel (1/ Req) = (1/ R1) + (1/ R2) + (1/ R3) …
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Capacitors
• Opposite formulae compared with resistors • Series (1/ Ceq) = (1/ C1) + (1/ C2) + (1/ C3) • Parallel
Ceq = C1 + C2 + C3 …
Inductors
• Similar formulae as for resistors • Series
Leq = L1 + L2 + L3 …
• Parallel (1/ Leq) = (1/ L1) + (1/ L2) + (1/ L3)
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Transformer Characteristics
• Voltage ratio Vsec / Vpri = Nsec / Npri • Current ratio Isec / Ipri = Npri / Nsec • Impedance Zsec / Zpri = (Nsec / Npri)2 where N is the number of turns
Series and Parallel Configuration
Batteries in Series
Batteries in Parallel
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Decibels Decibels are always a ratio of some quantity, and are often referenced to one particular level. The decibel symbol is dB, but if it is relative to something a suffix denotes what that is. Power Levels are quoted in dBW, which are dB relative to 1 Watt. For Power Ratios relative to 1 Watt :*Power, dBW = 10 x Log10 P(OUTPUT) / P(INPUT)
(Power output divided by Power input)
*Note: Voltage ratios in Amplifiers are 20 x Log10 VIN / VOUT Power, dBW 0dBW 3dBW 6dBW 9dBW 10dBW 20dBW 26dBW
1 Watt 2 Watts 4 Watts 8 Watts 10 Watts 100 Watts 400 Watts
Note that 3dB is a ratio of 2:1, and 10dB is a ratio of 10:1 Example-1: Thus 50 Watts can be derived from:100 Watts (20dBW) minus 3dB = 17dBW Example-2: 5 Watts is a half of 10 Watts:10dBW-3dB=7Dbw OR…
It’s a tenth of 50 Watts:17dBW-10dB=7dBW
Antenna Gain should be quoted as: dBi ( relative to an ideal isotropic radiator), or dBd (relative to a Dipole). 0dBd = 2.15dBi, (Note: antenna gain specs can be ‘enhanced’ if the reference is not given.) IRTS Region 4 Classes 2010
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Frequency and Wavelength
Frequency Band 1357 -1378 kHz 1810 - 2000 kHz 3.50 - 3.80 MHz 7.00 - 7.20 MHz 10.10-10.15 MHz 14.00 -14.350 MHz 18.068 -18.168 MHz 21.00 - 21.45 MHz 24.89 - 24.99 MHz 28.00 - 29.70 MHz 50.00 - 52.00 MHz 144.0 -146.0 MHz 430.0 – 440.0 MHz
Metre Band 1750 metres 160 metres 80 metres 40 metres 30 metres 20 metres 7 metres 15 metres 12 metres 10 metres 6 metres 2 metres 70 centimetres
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Meaning and use of Abbreviations CQ DE DX
General Call to all Stations From (This is) Long Distance
R RST SIG UR WX
Received Readability, Signal Strength, Tone Signal Your Weather
Very subjective - normally assume any place outside of the continent
Signal Reporting – RST Format Readability 1 2 3 4 5
Unreadable Barely Readable, occasional word distinguishable Readable with considerable difficulty Readable with practically no difficulty Perfectly readable
Signal 1 2 3 4 5 6 7 8 9
Faint, signals barely perceptible Very weak signals Weak signals Fair Signals Fairly good signals Good signals Moderately strong signals Strong signals Extremely strong signals
Tone 1 2 3 4 5 6 7 8 9
Extremely rough hissing noise Very Rough AC Note No Trace Of Musicality Rough low-pitched ac note, slightly musical Rather rough ac note, moderately musical Musically modulated note Modulated note, slight trace of whistle Near dc note smooth ripple Good dc note just a trace of ripple Purest dc note
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Phonetic Alphabet
A
Alpha
B
Bravo
C
Charlie
D
Delta
E
Echo
F
Foxtrot
G
Golf
H
Hotel
I
India
J
Juliet
K
Kilo
L
Lima
M
Mike
N
November
O
Oscar
P
Papa
Q
Quebec
R
Romeo
S
Sierra
T
Tango
U
Uniform
V
Victor
W
Whiskey
X
X-ray
Y
Yankee
Z
Zulu
The Phonetic Alphabet is used in radio messages to help avid errors when spelling a name or place Example
EI7JKB
Echo India Seven Juliet Kilo Bravo
EI7JKB/P Echo India Seven Juliet Kilo Bravo Portable EI7JKB/M Echo India Seven Juliet Kilo Bravo Mobile
ITU Regions
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Quantity Voltage, V Current, I Resistance, R Power, P Frequency, f Wavelength,
Unit Volt Amp Ohm Watt Hertz Metre
Symbol V A W Hz m
Resistance colour codes
Remembering the Colour Code: The colouring starts with Black (which is Zero). The sequence is: 0 1 2 3 4 5 6 7 8 9
Black, Brown, Red, Orange, Yellow, Green. Blue, Violet, Grey, and White. Just remember the ditty:
"Better Be Right Or Your Great Big Venture Goes West" Remember that it starts at Zero which is Black!
Bipolar Transistors
Collector
Base
Collector
Base
Emitter
Emitter
NPN
PNP
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Schematic Symbols
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Know your Transmitters
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Know your Receivers
Modulation
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Efficiency Class A
25% - 30 %
Class AB
50% - 60%
Class B
65% Approx
Class C
80%
Feedback Positive Feedback: used in oscillators Negative Feedback: used in automatic level control, automatic gain control (ALC & AGC) and distortion reduction.
Feedback Loop
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Filters
&
EMC/EMI
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Transmission Lines Open Wire: 600ohm; 300ohm; 150 ohm
Ladder Cable; Ribbon Cable
Coaxial: 50ohm 75ohm
Velocity Factor: always < 1 ; Coaxial cable could be as low as 0.66
Properties of Transmission Lines of Various Lengths and Terminations
/4
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Antenna Wire Antenna:
Related to wavelength;
horizontal; vertical
Multi element Antenna:
Beam; Yagi; Log-periodic;
Driven Element; Reflector; Directors
Dish; Parabolic Reflectors: Sat TV; Radar Radiation Patterns:
Directional; Omni-directional
Gain:
dBd;
dBi
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Propagation
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Comreg What are ComReg’s concerns relating to the Licencing of Radio Amateurs? That you: Have sufficient technical expertise Comply with the Regulations interference to other users of the Electromagnetic Spectrum adhering to licenced bands adhering to operating procedures and guidelines
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