Accelerated Technician Class
Session #4
Data and RTTY
RTTY (radio teletype) was the forerunner of all
modern digital mode transmission.
Today, amateurs use many kinds of intelligent
on air networking modes. Collectively, the FCC
refers to these intelligent modes as “Data.”
Both Data and RTTY require an interface
between the Data or RTTY device and the
transceiver.
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Data
vs.
Error correcting
Store and forward
networking
Addressable
Packet oriented
Will interface with
the internet
Requires TNC to
interface with radio
RTTY
No error correction
Direct contact
No addressing
Continuous data
stream
No way!!
Requires “modem”
to interface with
radio
A Packet Network
With only a few watts, you can connect to an
on
on--air network. Your data packets will be
forwarded to hams all over the country.
Packet type protocols include:
Packet and APRS,
COVER,
PACTOR I, II & III
G-TOR
(This is what TSA uses for HF Email)
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A Packet Network
A Packet Network
A digipeater is a
packet--radio station
packet
capable of recognizing
and selectively repeating
packet frames.
All the stations on a
packet network share
the same frequency.
By the use of digipeaters,
a packet can be reliably
sent error free over great
distances.
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TNCs
The “Terminal Node Controller” (TNC)
interfaces your computer to your transceiver.
TNCs (like the old dial up modems we used to get on the Internet)
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Test, SS and Pulse
Test emissions are simply unmodulated
carrier.
SS (Spread Spectrum) are experimental
frequency hopping modes.
Pulse emissions are used for telemetry.
What method of call sign identification is
required for a station transmitting phone
signals?
A. Send the call sign followed by the indicator
RPT
B. Send the call sign using CW or phone
emission
C. Send the call sign followed by the indicator
R
D. Send the call sign using only phone
emission
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Which of the following would be connected
between a transceiver and computer in a packet
radio station?
A. Transmatch
B. Mixer
C. Terminal node controller
D. Antenna
What happens when the deviation of an
FM transmitter is increased?
A. Its signal occupies more bandwidth
B. Its output power increases
C. Its output power and bandwidth increases
D. Asymmetric modulation occurs
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Which type of modulation is most commonly
used for VHF and UHF voice repeaters?
A. AM
B. SSB
C. PSK
D. FM
What can you do if you are told your
FM handheld or mobile transceiver is
over deviating?
A. Talk louder into the microphone
B. Let the transceiver cool off
C. Change to a higher power level
D. Talk farther away from the microphone
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Antennas
Antennas and Feed lines
Most antenna systems are resonant - that is,
they respond best at a certain frequency.
For best operation, the transmitter, feed line
and antenna should all be matched to the
same impedance.
The transmitting antenna induces a radio
wave into the air. The radio wave travels to
the receiving antenna, and induces a current
in that antenna.
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The 1/2 Wave Dipole
Length of dipole in feet =
468
f (MHz)
The 1/2 Wave Dipole
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The 1/4 Wave Vertical
Length of vertical in feet =
234
f (MHz)
The 1/4 Wave Vertical
A side view of the radiation pattern of a 1/4 wave
vertical. From above the pattern is round like a
doughnut. A perfect ground would be a car roof.
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The Yagi (Type of Beam Antenna)
The yagi is the ham’s favorite directional
antenna.
They usually consist of one driven element,
and several “parasitic” (un(un-driven) elements.
Reflector (longer than driver)
Driven Element (1/2 wave dipole)
One or more Directors (shorter than the driven
element)
The director
acts like a
lens
Director
Boom
Feedline
Reflector
The reflector
acts like a
mirror
Driver
The Yagi
Gain
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The Yagi
The yagi antenna focuses RF energy in
one direction, giving the appearance of
getting “free power.”
This free power is called Antenna Gain.
The Yagi (Beam Antenna)
A 3 element HF Yagi
A VHF Yagi
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Feed lines
Feed line connects your radio to the antenna.
Feed lines are either balanced (neither side
grounded) like ladderladder-line or unbalanced (one
side grounded) like coaxial cable.
Either type can be used in your station.
Coax is more popular and easier to work
with.
Coax
vs.
Can be buried or run
near metal objects.
Less RFI since outer
shield is usually
grounded.
Weatherproof
Easy to handle and
connect
Ladder Line
Very low signal loss
Can tolerate high
SWR
Can tolerate high
current
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Coax
All coaxial cable
will feature a
center conductor
surrounded by a
dielectric insulator
and one or more
layers of shielding
and an insulating
cover.
The Balun
The balun converts from
BALanced
BAL
anced feed line to
UNbalanced
UNbalanced feed lines.
Many antenna systems work
better with a balun between
the feed point and the coax
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SWR
SWR (standing wave ratio) is a mathematical
expression of the power going to an antenna
and the power being reflected back.
The idea is to get as close to 1:1 as possible.
Most hams are happy with SWR of <1.5:1.
Most transmitters are happy with SWR of <2:1.
The best way to get a good SWR is to cut the
antenna to resonance.
The Antenna Tuner
“Antenna Tuners” do not really tune antennas.
They provide an impedance match between
the transmitter and antenna system.
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What does an antenna tuner do?
A. It matches the antenna system impedance
to the transceiver's output impedance
B. It helps a receiver automatically tune in
weak stations
C. It allows an antenna to be used on both
transmit and receive
D. It automatically selects the proper antenna
for the frequency band being used
What is the approximate length, in inches, of a
6 meter 1/2-wavelength wire dipole antenna?
A. 6
B. 50
C. 112
D. 236
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What is the approximate length, in inches, of
a quarter-wavelength vertical antenna for 146
MHz?
A. 112
B. 50
C. 19
D. 12
How would you change a dipole antenna to
make it resonant on a higher frequency?
A. Lengthen it
B. Insert coils in series with radiating wires
C. Shorten it
D. Add capacity hats to the ends of the
radiating wires
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Which of the following describes a simple
dipole mounted so the conductor is parallel to
the Earth's surface?
A. A ground wave antenna
B. A horizontally polarized antenna
C. A rhombic antenna
D. A vertically polarized antenna
What type of antennas are the quad, Yagi,
and dish?
A. Non-resonant antennas
B. Loop antennas
C. Directional antennas
D. Isotropic antennas
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What is a disadvantage of the "rubber duck"
antenna supplied with most handheld radio
transceivers?
A. It does not transmit or receive as effectively
as a full-sized antenna
B. It transmits a circularly polarized signal
C. If the rubber end cap is lost it will unravel
very quickly
D. All of these choices are correct
What, in general terms, is standing wave ratio
(SWR)?
A. A measure of how well a load is matched to
a transmission line
B. The ratio of high to low impedance in a
feedline
C. The transmitter efficiency ratio
D. An indication of the quality of your station’s
ground connection
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Intermission
RF Safety
Can’t touch this.
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2 Types of Radiation
Ionizing
Gamma and XX-ray
Can cause ionization of atomic structure
Not good for your DNA
Non--ionizing
Non
Radio waves
Can cause heating of biological tissue
If sufficient energy is present, can cause burns
RF Heating
Radio waves can heat body tissue.
Works exactly like your microwave oven.
The area most likely to be injured is the eye
as it lacks sufficient blood flow for cooling.
The eye can form cataracts from repeated
exposure to high levels of RF energy.
NEVER touch an antenna or other RF source.
You could be severely burned.
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Controlled and Uncontrolled
Environments
Controlled Environments
The amateur operators household and property
Persons here are aware of RF risks, and have
control of the transmitting equipment.
Uncontrolled Environments
Your neighbors household and property
Persons here are generally not aware of RF risks
and have NO control over the transmitter.
Exposure Averaging Times
Controlled Environments
The exposure averaging time is
6 Minutes
Uncontrolled Environments
The exposure averaging time is
30 Minutes
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3 Methods of RF Checking
Measure the RF fields
Requires costly equipment that you don’t have
Calculate the RF fields
Requires software that you may or may not have
Use the charts published by the FCC
The charts are free
Fairly simple to use
RF Safety for Dummies
Install your antenna away from people,
especially your neighbors. The higher
the better.
Make sure your antenna is not near or
could fall on a power line.
Keep your hands and other body parts
away from the antenna and feed lines.
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Who is Exempt?
Nobody -- The RF safety regulations apply to ALL
amateur stations.
However, the following stations are “categorically
exempt” from having to do a routine station
evaluation:
Mobile & handhand-held radios using PTT control.
Any station that produces less than 50 watts PEP
output.
What is the minimum safe distance from a power line
to allow when installing an antenna?
A. Half the width of your property
B. The height of the power line above ground
C. 1/2 wavelength at the operating frequency
D. So that if the antenna falls unexpectedly, no part of
it can come closer than 10 feet to the power wires
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What is the maximum power level that an
amateur radio station may use at VHF
frequencies before an RF exposure evaluation
is required?
A. 1500 watts PEP transmitter output
B. 1 watt forward power
C. 50 watts PEP at the antenna
D. 50 watts PEP reflected power
What could happen if a person accidentally
touched your antenna while you were
transmitting?
A. Touching the antenna could cause
television interference
B. They might receive a painful RF burn
C. They might develop radiation poisoning
D. All of these choices are correct
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Why is duty cycle one of the factors used to
determine safe RF radiation exposure levels?
A. It affects the average exposure of people
to radiation
B. It affects the peak exposure of people to
radiation
C. It takes into account the antenna feedline loss
D. It takes into account the thermal effects of
the final amplifier
Which of the following actions might amateur
operators take to prevent exposure to RF
radiation in excess of FCC-supplied limits?
A. Relocate antennas
B. Relocate the transmitter
C. Increase the duty cycle
D. All of these choices are correct
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Questions?
What to Expect at the Exam Session
There is no fee.
All the elements will be offered.
Bring photo identification.
The tests are not timed.
Bring a #2 pencil.
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What to Expect at the Exam Session
You can bring a calculator.
Do not write in the test booklet.
Use back side of answer sheet for scratch paper
You can retest any time, even at the same
session.
The Element 2 - Technician Class Exam consists
of 35 multiple choice questions, (you can miss
9) and you must answer 75% or better to pass.
Who passes the
exams?
Those who:
• Prepare by studying 30
minutes to one hour a
day.
• Take their time on the
exam.
• Ask for help from an
Elmer.
Keep trying, Never ever give up!!!!!!
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Your New Call Sign
You can get on the air as soon as you
know your new call sign.
Visit the FCC Universal Licensing System on
www.fcc.gov
Do a Name Search on www.qrz.com,
www.qrz.com, 6 - 8
days after you pass your exam.
Your license will arrive in the mail in a
week or so.
Welcome to the World of
Amateur Radio
What to do with that new call sign
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Now that I am a Amateur Radio
Operator, What Do I Do?
Support Amateur Radio locally. Be involved in
local clubs and associations.
Get involved in community service through
your local ARES or RACES group.
Join the American Radio Relay League (ARRL)
More importantly, get on the air and say
something!
ARES
ARES is the local
community emergency
services organization
where hams can serve
as only amateur radio
can…providing
communications for
emergencies and
special events.
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Why join the ARRL?
Since 1914 the American Radio
Relay League has represented the
interests of Radio Amateurs before
the FCC and Congress. While there
is room for policy debate, those
who do not support the ARRL have
virtually no voice in matters
concerning ham radio. Also, the
QST magazine is an excellent
educational tool, full of interesting
articles and fun projects.
Where do I go from here?
Stamp Collecting
Meteorology
Geography
Computers
Radio Astronomy
Emergency Services
Support your local Amateur Radio organization!
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This Completes the Course…
…and begins a worldwide journey that
will last you a lifetime.
Enjoy your new hobby!
73, de the WVARA Education Committee
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