Transcript Slide 1

Equipment
Let’s look at some more basic
radio components...
Release 1.0 – September 2006
1
The Microphone
In a basic amateur
radio station, the
microphone connects to the
transmitter. It converts
the sound energy generated
by your voice into a tiny
electrical signal that
“modulates” the radio wave
generated by the
transmitter. This is how
your voice gets carried out
over the air. The
microphone may be a device
that connects to the radio
through a plug, or in
smaller radios such as a
handheld, it may be built
into the radio.
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2
The Speaker
At the radio on the other end, your signal
comes into the receiver and that same electrical
energy produced by the sound of your voice is
stripped away from the radio wave by a process
called “demodulation.” It is then amplified and
fed into a speaker. The piece of station equipment
that converts the electrical signals to sound
waves you can hear is the speaker.
The speaker may be built into the radio, or it
may be an external speaker that plugs into the
radio, similar to stereo speaker.
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Audio Feedback
Have you ever seen someone get a
microphone too close to an amplifier
or speaker? It can produce an awful
squeal. The term used to describe
what happens when a microphone and
speaker are too close to each other
is “audio feedback.” If you hear
it, the remedy is usually to move
the microphone away from the speaker
or amplifier.
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Headphones
Everybody knows what
headphones are. You can use
headphones instead of a regular
speaker to help you copy
signals in a noisy area. But
be careful! Listening through
headphones with too much volume
can be harmful to your hearing.
(We’ll bet your mother already
told you that!)
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Regulated Power Supply
You have already learned that the power supply
converts household AC to the correct DC voltage
for a radio. But some power supplies are not all
that great at maintaining a steady voltage. If
the load on those supplies increases, it can pull
the voltage down. Such power supplies are
“unregulated.”
The better power supplies have devices in them
that will allow them to maintain the same voltage
so long as the maximum load is not exceeded.
These are called “regulated” power supplies. A
good reason for using a regulated power supply for
communications equipment is to protect equipment
from voltage fluctuations (changes).
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Filters
In the radio world, an emission is something
coming out of the transmitter and going to the
antenna. The idea is that the only signal you
want going into your antenna is the one for the
frequency you intend to be on.
Sometimes, a transmitter will produce spurious
emission on frequencies where you don’t want them.
(Cheap – and illegal – CB amps are really bad for
producing spurious emission that are heard in
TV’s, stereos, and PA systems!)
When you have spurious emissions, you need to
install a special filter to get rid of these
spurious emissions. To reduce spurious emissions
a filter must be installed at the transmitter.
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Notch Filters
Sometimes an amateur radio, such as a 2
meter transmitter, can overload a nearby
television causing it to not play
properly. When this happens, you need a
filter at the television that will filter
out signals above and below the TV
channels.
This type of filter is called a “notch
filter. As a first step in trying to
prevent RF overload from a nearby 2-meter
transmitter to a TV receiver, you should
install a notch filter on the TV at the
antenna input.
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Terminal Node Controller
Most new hams today use computers with their
radios. One use is to send and receive “packet”
messages and data. Packet allows text messages
and data files to be sent between two ham stations
over the air in pieces called “packets.” These
packets are put together at the receiving station
into a complete text or computer file.
You have to have a device to interface between
the radio and the computer to do packet radio. In
a packet radio station, a “terminal node
controller” is connected between the transceiver
and computer terminal.
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More on Packet
Because the data being
transmitted by packet begins at
the computer keyboard, or with
a file inside the computer, a
microphone is not required for
a packet radio station.
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Computer Sound Cards
More and more, the computer sound
card is replacing the terminal node
controller for packet and other
digital modes. With the right
software, which is often free, the
sound card can be used to connect a
radio with a computer for data
transmission and reception. There
are a number of programs that make
use of the sound card to operate
many newer modes such as PSK31.
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Check-Up Time!
Now let’s try the questions from
this group.
You should make a note of any that
you miss for later review.
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12
T5A01
What does a microphone connect
to in a basic amateur radio
station?
A.
B.
C.
D.
The
The
The
The
receiver
transmitter
SWR Bridge
Balun
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T5A01 Answer - B
The microphone is connected
to the transmitter (or the
transmitter portion of a
transceiver). When you speak
into the microphone, it changes
the energy from the sound waves
of your voice to electrical
energy that modulates the
transmitted signal.
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T5A02
Which piece of station
equipment converts electrical
signals to sound waves?
A.
B.
C.
D.
Frequency coordinator
Frequency discriminator
Speaker
Microphone
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T5A02 Answer - C
The receiver removes the
electrical signal representing
the other operator’s voice from
the radio signal and amplifies
it. The voice signal is then
fed into the speaker which
changes that electrical energy
into sound that can be heard.
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T5A03
What is the term used to
describe what happens when a
microphone and speaker are too
close to each other?
A.
B.
C.
D.
Excessive wind noise
Audio feedback
Inverted signal patterns
Poor electrical grounding
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T5A03 Answer - B
You have probably heard
feedback when a microphone was
placed too close to a speaker
in a sound system. It usually
starts as a low squeal, but if
the microphone is not moved
away from the speaker, it can
quickly become very loud and
very unpleasant.
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T5A04
What could you use in place of
a regular speaker to help you
copy signals in a noisy area?
A.
B.
C.
D.
A
A
A
A
video display
low pass filter
set of headphones
boom microphone
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T5A04 Answer - C
This one should be obvious to
you if you have ever put on a
set of headphones to block out
the noise around you. It works
great for amateur radio,
especially if you are trying to
copy Morse code!
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T5A05
What is a good reason for using a
regulated power supply for communications
equipment?
A. To protect equipment from voltage
fluctuations
B. A regulated power supply has FCC approval
C. A fuse or circuit breaker regulates the
power
D. Regulated supplies are less expensive
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T5A05 Answer - A
A regulated power supply costs
more than an unregulated one, but
the voltage it puts out remains
constant, even when the current
drawn from the supply changes. An
unregulated supply may vary plus or
minus several volts from its rating,
and that voltage fluctuation can
damage sensitive equipment, so a
good regulated supply is always much
better.
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T5A06
Where must a filter be
installed to reduce spurious
emissions?
A.
B.
C.
D.
At
At
At
At
the
the
the
the
Release 1.0 – September 2006
transmitter
receiver
station power supply
microphone
23
T5A06 Answer - A
Spurious emissions are
unwanted signals produced by a
transmitter. These must be
filtered out in the transmitter
before the signal is fed into
an antenna.
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T5A07
What type of filter should be
connected to a TV receiver as the
first step in trying to prevent RF
overload from a nearby 2-meter
transmitter?
A.
B.
C.
D.
Low-pass filter
High-pass filter
Band pass filter
Notch filter
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T5A07 Answer - D
A television that is being
disrupted by a 2 meter radio signal
is receiving harmonic signals that
it should not be receiving. A welldesigned set should not have this
problem. However, placing a notch
filter at the antenna input of the
TV will allow it only to receive the
signals it is supposed to and will
notch out everything above and below
those signals.
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T5A08
What is connected between the
transceiver and computer
terminal in a packet radio
station?
A.
B.
C.
D.
Transmatch
Mixer
Terminal Node Controller
Antenna
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T5A08 Answer - C
Think of the terminal node
controller (or TNC) as the device
that allows the radio and the
computer to talk to one another,
because that is basically what it
does. Signals received by the
radio, when sent through the TNC can
be decoded into text by the
computer. Likewise, the text
generated by the computer is
translated by the TNC into a signal
that may be transmitted.
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T5A09
Which of these items is not
required for a packet radio
station?
A.
B.
C.
D.
Antenna
Transceiver
Power source
Microphone
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T5A09 Answer - D
“Packet” is a mode of
communications where text is sent
and received by a computer through a
radio. It works very much like
instant messenger systems on a
computer, except that it is sent
over the air rather than by the
Internet. Since text is being sent
and received, no microphone is
required.
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T5A10
What can be used to connect a
radio with a computer for data
transmission?
A.
B.
C.
D.
Balun
Sound Card
Impedance matcher
Autopatch
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T5A10 Answer - B
At one time, a terminal node
controller (TNC) was required
to interface between a computer
and the radio. However, with
better and faster computers, a
good computer sound card can
connect the radio and computer
for many digital modes such as
PSK and slow scan television
(SSTV).
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Group T5B
Group T5B covers the basic
operating controls of a
typical Technician amateur
radio station .
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Microphone Gain
Most transceivers have a
microphone gain control. This
control adjusts the electrical
signal generated by your microphone,
and it can amplify that signal
before it modulates the radio
signal. However, the gain must not
be set too high. If a transmitter
is operated with the microphone gain
set too high, it may cause the
signal to become distorted and
unreadable.
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Transceiver Memory
Most modern VHF/UHF transceivers
have built in memory that is capable
of storing much information. Among
the kinds of information a VHF/UHF
transceiver is capable of storing in
memory are the transmit and receive
operating frequency, CTCSS tone
frequency, and transmit power level.
In fact, one way to enable quick
access to a favorite frequency on
your transceiver is to store the
frequency in a memory channel.
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Frequency Selection
In many modern
transceivers, you can
select the operating
frequency in either
one of two ways. You
can either use the
keypad, usually
located on the
microphone, to enter
the desired
frequency, or you can
use the VFO knob to
enter the correct
frequency.
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Squelch Control
Most radios also have a squelch
control. The purpose of the squelch
control on a transceiver is to quiet
noise when no signal is being
received. Without the squelch
control, when there is no signal
present, you will hear “white noise”
or static. By adjusting the squelch
control, the receiver will remain
silent until there is a signal
strong enough to “break” the squelch
and be heard in the receiver.
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Noise Blanker
Another feature on many
transceivers is a “noise
blanker.” The purpose of this
device is to decrease noise
caused by static and ignition.
If a station you are listening
to is hard to copy because of
ignition noise interference,
you might turn on the noise
blanker to improve reception.
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“Up” and “Down” Buttons on
the Microphone
Many transceiver microphones
have buttons labeled "up" and
"down" on them. The purpose of
these buttons is to allow easy
frequency or memory selection.
These buttons are similar to
the up and down buttons on a TV
remote or car radio.
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Shift Control
Most UHF/VHF transceivers have a
“shift” control. The purpose of the
"shift" control on VHF/UHF transceivers is
to adjust the offset between transmit and
receive frequency. You may recall that
most repeaters transmit on one frequency
and receive on another, so any radio that
is going to use the repeater needs to be
able to transmit on the repeater’s receive
frequency (input) and receive on the
repeater’s transmit frequency (output).
The shift control lets the operator make
this adjustment.
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Receiver Incremental
Tuning (RIT)
The acronym “RIT”
stands for “receiver
incremental tuning.”
This control is
generally used when
sending and receiving
Morse code. It allows
you to adjust the
frequency of the
receiver slightly so
that the tone of the
received code is
comfortable to your
ear without changing
the transmit
frequency.
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Step Function
The “step function” is an option found
on many radios. The purpose of the "step"
function is to set the tuning rate when
changing frequencies. This allows the
operator to change frequencies quickly by
moving up or down is incremental steps.
For example, if the step function is set
at 1 MHz, then as the dial is tuned or the
“up” or “down” buttons are pushed, the
frequency steps up or down by 1 MHz at a
time.
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Function Key
Many transceivers include a
"function" or "F" key. The purpose
of this key is to select an
alternate action for some control
buttons. This is similar to the
function key on many calculators and
computers. By pressing the function
key at the same time as some other
control key, it allows that key to
be used for more than one purpose.
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Check-Up Time!
Now let’s try the questions from
this group.
You should make a note of any that
you miss for later review.
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44
T5B01
What may happen if a transmitter is
operated with the microphone gain
set too high?
A. The output power will be too high
B. It may cause the signal to become
distorted and unreadable
C. The frequency will vary
D. The SWR will increase
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T5B01 Answer - B
Setting the microphone gain
too high on FM may cause your
voice to be distorted. On
sideband, it may also cause
your signal to “splatter”
outside the proper bandwidth of
the signal, resulting in
harmful interference. Either
way, you’ll sound bad on the
air.
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T5B02
What kind of information may a
VHF/UHF transceiver be capable of
storing in memory?
A. Transmit and receive operating
frequency
B. CTCSS tone frequency
C. Transmit power level
D. All of these answers are correct
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T5B02 Answer - D
Most modern transceivers have
built in memory that is capable
of storing all the information
listed in this question and a
whole lot more.
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T5B03
What is one way to select a
frequency on which to operate?
A. Use the keypad or VFO knob to
enter the correct frequency
B. Turn on the CTCSS encoder
C. Adjust the power supply ripple
frequency
D. All of these answers are correct
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T5B03 Answer - A
Most handheld radios have a
keypad on the radio that allows you
to enter the frequency you want by
pressing the buttons. Most larger
radios have a VFO (variable
frequency oscillator) knob that lets
you spin the knob to dial in the
frequency you want.
Many radios, whether large or
small, may have both.
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T5B04
What is the purpose of the squelch
control on a transceiver?
A. It is used to set the highest
level of volume desired
B. It is used to set the transmitter
power level
C. It is used to adjust the antenna
polarization
D. It is used to quiet noise when no
signal is being received
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T5B04 Answer - D
The squelch control keeps the
radio quiet when no signal is
being received. With the
squelch off, you generally hear
a rushing sound when no signal
is present. This rushing sound
is sometimes called “white
noise.”
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T5B05
What is a way to enable quick access
to a favorite frequency on your
transceiver?
A. Enable the CTCSS tones
B. Store the frequency in a memory
channel
C. Disable the CTCSS tones
D. Use the scan mode to select the
desired frequency
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T5B05 Answer - B
Just like your car radio, a
modern ham radio can store
several of your favorite
frequencies in its internal
memory. This is a particularly
good way to easily get to your
favorite repeaters with the
touch of a button.
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T5B06
What might you do to improve the
situation if the station you are
listening to is hard to copy because
of ignition noise interference?
A.
B.
C.
D.
Increase your transmitter power
Decrease the squelch setting
Turn on the noise blanker
Use the RIT control
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T5B06 Answer - C
The “noise blanker” helps to
reduce or eliminate some types
of interference such as
electrical noise.
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T5B07
What is the purpose of the buttons
labeled "up" and "down" on many
microphones?
A. To allow easy frequency or memory
selection
B. To raise or lower the internal
antenna
C. To set the battery charge rate
D. To upload or download messages
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T5B07 Answer - A
The “up” and “down” buttons
on the microphone allow you to
quickly shift your frequency up
or down by just pressing the
button until you get to the
desired frequency.
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T5B08
What is the purpose of the "shift"
control found on many VHF/UHF
transceivers?
A. Adjust transmitter power level
B. Change bands
C. Adjust the offset between transmit
and receive frequency
D. Change modes
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T5B08 Answer - C
VHF and UHF repeaters operate on
split frequencies. The repeater
transmits on one frequency and
receives on another. In order to
use a repeater, your radio has to
transmit on the repeater’s receive
frequency, and receive on the
repeater’s transmit frequency. The
“shift” control automatically
adjusts your radio to the proper
split.
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T5B09
What does RIT mean?
A.
B.
C.
D.
Receiver Input Tone
Receiver Incremental Tuning
Rectifier Inverter Test
Remote Input Transmitter
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T5B09 Answer - B
“Receiver incremental tuning”
or RIT, allows you to adjust
your receive frequency so that
it is slightly off from your
transmit frequency. This is
sometimes useful when you are
working Morse code on
continuous wave (CW).
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T5B10
What is the purpose of the "step"
menu function found on many
transceivers?
A. It adjusts the transmitter power
output level
B. It adjusts the modulation level
C. It sets the earphone volume
D. It sets the tuning rate when
changing frequencies
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T5B10 Answer - D
The “step” function can save you
time while tuning by allowing you to
jump up or down in frequency by a
fixed amount. For example, you
could set the “step” function to
allow you to increase or decrease
your frequency one megahertz at a
time, rather than spinning the
tuning knob several times to move
that distance.
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T5B11
What is the purpose of the
"function" or "F" key found on many
transceivers?
A. It turns the power on and off
B. It selects the autopatch access
code
C. It selects an alternate action for
some control buttons
D. It controls access to the memory
scrambler
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T5B11 Answer - C
You are probably already
familiar with the function keys
on a computer keyboard. The
function button on a radio
generally serves the same
purpose. When you press the
function button plus another
button, the radio uses that
button for a different purpose.
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Group T5C
Group T5C covers the use of repeaters
including repeater and simplex operating
techniques, offsets, selective squelch,
open and closed repeaters, and linked
repeaters.
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More on Repeaters
As a Technician, one of
the first things you will want
to do is get a VHF/UHF radio
that is capable of working
through repeaters. An amateur
repeater usually has an output
power that is greater than a
typical transceiver, and the
antenna is mounted on top of a
large structure such as a tall
tower, building or water
tower, or on the top of a high
natural feature such as a
mountain top. By having a
greater power and being
mounted high above the
terrain, one major purpose of
a repeater is to extend the
usable range of mobile and
low-power stations.
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The W4BWC Repeater
Many hams
have never seen
an amateur
radio repeater.
Here is what a
typical twometer repeater
looks like.
This one is the
W4BWC repeater,
located in
Raleigh, N.C.,
and is typical
of ham
repeaters.
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Courtesy Tones
Most repeaters have a
courtesy tone that sounds at
the end of a transmission just
before the repeater stops
transmitting or “drops out.”
The courtesy tone indicates
that a transmission is complete
and that it is OK to respond to
the person transmitting.
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Wait Before You Speak!
When using a repeater, you should
you pause briefly between
transmissions in order to listen for
anyone wanting to break in. You
never know when someone might be
involved in an emergency and needs
to request assistance. If each
repeater user waits just a second
before transmitting, that will give
someone a chance to break in with
their call.
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Repeater Splits
Up to now, you have seen that
repeaters receive signals on one
frequency and retransmit those same
signals on another frequency. In
order to use any repeater, the most
important information to know is the
repeater input and output
frequencies. The separation between
the transmit and receive frequencies
is called the “repeater split,” and
we’ll take a look at that those
next.
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2 Meter Repeater Split
Without knowing the repeater split, you
cannot set your own radio to work the
repeater. The transmit and receive
frequencies could be any two frequencies
on the part of the band that allows
repeaters, but that could quickly become
confusing. This problem is fixed by a
voluntary system where these splits are
set up to be standard for each band.
The most common input/output frequency
offset for repeaters in the 2-meter band
is 0.6 MHz (or 600 KHz).
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70-Centimeter Repeater
Split
The most common input/output
frequency offset for repeaters in
the 70-centimeter band is 5.0 MHz.
As you can see, the frequency
separation is much greater than for
2 meters. Nothing in Part 97
explicitly requires any standard
split, so compliance is voluntary.
However, it is in the repeater
owner’s best interest to comply. It
reduces the possibility of
interference between repeaters.
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Coordinated Repeaters
Most repeaters are now coordinated by a
local frequency coordinator. Although it
is not mandatory to coordinate repeaters,
the main reason repeaters should be
approved by the local frequency
coordinator before being installed is that
coordination minimizes interference
between repeaters and makes the most
efficient use of available frequencies.
The frequency coordinator will use
information about other local repeaters to
assign a repeater channel and split that
is not likely to cause interference to
other repeaters in the area.
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Linked Repeaters
A series of repeaters that can be
connected to one another to provide users
with a wider coverage is called a linked
repeater system. The advantage of a
linked repeater system is that it enables
repeater communications over a long
distance. Some linked repeater systems
are capable of communications over
hundreds of miles. The disadvantage of
linking repeaters is that it ties up all
the repeaters in the link for a single
communications channel.
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Repeater Access
Access to any repeater may be
limited by the repeater owner.
Fortunately, most repeater
owners maintain open repeaters.
These machines are put into
service at great effort and
expense to the owner, and
privilege of using them should
never be abused.
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Closed Repeaters
A group of amateurs may decide to
establish a “closed repeater.” A
closed repeater is a repeater whose
use is restricted to the members of
a club or group and is not available
for everyone to use. This is
perfectly legal. Although no
amateur has the exclusive right to
any frequency, neither does any
amateur have any right to access a
repeater.
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Simplex Operation
Repeaters require two frequencies
to operate. When two frequencies
are used to communicate, this is
called “duplex operation.” There
are many times when it is practical
for two stations to operate without
using a repeater. In such cases,
both stations will use the same
frequency. When two stations are
communicating by transmitting and
receiving on the same frequency,
this is known as simplex operation.
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Why Use Simplex?
In many cases, it is possible for two stations
to communicate using simplex. If two stations are
close enough to communicate without using the
repeater, they can pick an unused frequency
available for simplex and chat away without
worrying about tying up the repeater. This works
well when the stations are only a few miles apart
and have good antennas, when mobile stations are
traveling alongside one another, or when portable
stations are camping or hiking. Regardless, a
good reason to use simplex instead of a repeater
in such cases is to avoid tying up the repeater
when direct contact is possible.
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Will Simplex Work?
Suppose you are talking to another station and
you want to know whether you are close enough to
use simplex instead of the repeater. One way to
find out is switch your receiver so that you are
listening to the repeater’s input frequency. The
input frequency is the frequency that each station
transmits on. If you can hear the other station
on the input frequency, then you are not using the
repeater to hear him or her. If the other station
is also able to hear you on the input, the two of
you should be able to pick an available simplex
frequency and move off the repeater. So remember,
to find out whether you can communicate with a
station using simplex instead of a repeater, check
the repeater input frequency to see if you can
hear the other station.
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Check-Up Time!
Now let’s try the questions from
this group.
You should make a note of any that
you miss for later review.
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T5C01
What is one purpose of a repeater?
A. To cut your power bill by using
someone else's higher power system
B. To extend the usable range of
mobile and low-power stations
C. To transmit signals for observing
propagation and reception
D. To communicate with stations in
services other than amateur
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T5C01 Answer - B
A good repeater extends the range
stations can communicate because its
antenna is generally located high above
the ground. Because it is above any
obstructions that can get in the way,
radios with low power can reach the
repeater from much longer distances than
they could if the repeater was near to the
ground. This allows low power stations to
communicate with each other even when they
are located many miles apart.
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T5C02
What is a courtesy tone?
A. A tone used to identify the
repeater
B. A tone used to indicate when a
transmission is complete
C. A tone used to indicate that a
message is waiting for someone
D. A tone used to activate a receiver
in case of severe weather
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T5C02 Answer - B
The courtesy tone is a beep
or similar tone that sounds
when the repeater stops
transmitting. This happens
when the station whose signal
it is retransmitting releases
the microphone button.
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T5C03
Which of the following is the most
important information to know before
using a repeater?
A. The repeater input and output
frequencies
B. The repeater call sign
C. The repeater power level
D. Whether or not the repeater has an
autopatch
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T5C03 Answer - A
In order to use a repeater, you
must know the input and output
frequencies of that repeater. The
input frequency is the frequency you
must set as your transmit frequency
into the repeater. The output
frequency is the frequency the
repeater retransmits received
signals, and your receive frequency
must be set to that output
frequency.
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T5C04
Why should you pause briefly between
transmissions when using a repeater?
A. To let your radio cool off
B. To reach for pencil and paper so
you can take notes
C. To listen for anyone wanting to
break in
D. To dial up the repeater's autopatc
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T5C04 Answer - C
A repeater is like a single
channel that allows only one
conversation at a time. When
two or more people are talking
on a repeater, everyone should
pause in case someone else
wants to join the conversation
or needs to use the repeater
for an emergency. It’s just
good manners!
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T5C05
What is the most common
input/output frequency offset
for repeaters in the 2-meter
band?
A.
B.
C.
D.
0.6
1.0
1.6
5.0
MHz
MHz
MHz
MHz
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T5C05 Answer - A
On two meters, the transmit
and receive frequencies are
usually offset by .6 MHz
(megahertz). This is equal to,
and sometimes seen as 600 KHz
(kilohertz).
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T5C06
What is the most common
input/output frequency offset
for repeaters in the 70centimeter band?
A.
B.
C.
D.
600
1.0
1.6
5.0
kHz
MHz
MHz
MHz
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T5C06 Answer - D
For 70 cm, the offset is
generally 5 MHz (megahertz).
Repeater offsets have to be
memorized for the test, but
they are important to know when
you begin operating. And you
only have to know a couple of
them!
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T5C07
What is meant by the terms input and output
frequency when referring to repeater operations?
A. The repeater receives on one frequency and
transmits on another
B. The repeater offers a choice of operating
frequencies
C. One frequency is used to control the repeater and
another is used to retransmit received signals
D. The repeater must receive an access code on one
frequency before it will begin transmitting
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T5C07 Answer - A
A repeater works by receiving
signals on one frequency (the
input) and retransmitting those
signals on another frequency
(the output). The repeater
uses this split frequency
system so that stations using
it don’t interfere with it by
transmitting on the same
frequency it does.
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T5C08
What is the meaning of the term
simplex operation?
A. Transmitting and receiving on the
same frequency
B. Transmitting and receiving over a
wide area
C. Transmitting on one frequency and
receiving on another
D. Transmitting one-way
communications
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T5C08 Answer - A
When stations are communicating
by transmitting and receiving on the
same frequency, they are operating
simplex. Compare this to when
stations are operating through a
repeater using one frequency to
transmit and another to receive.
Stations working frequency splits,
such as through a repeater, are
working “duplex.”
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T5C09
What is a reason to use simplex
instead of a repeater?
A. When the most reliable
communications are needed
B. To avoid tying up the repeater
when direct contact is possible
C. When an emergency telephone call
is needed
D. When you are traveling and need
some local information
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T5C09 Answer - B
When two stations are within
a few miles of one another,
they can often communicate on
simplex and avoid tying up a
repeater. This allows the
repeater to be used by those
who are too far apart to work
simplex.
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T5C10
How might you find out if you could
communicate with a station using simplex
instead of a repeater?
A. Check the repeater input frequency to see
if you can hear the other station
B. Check to see if you can hear the other
station on a different frequency band
C. Check to see if you can hear a more
distant repeater
D. Check to see if a third station can hear
both of you
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T5C10 Answer - A
When using a repeater, you hear the
retransmitted signal through the
repeater’s output frequency. However, if
you can hear the station on the repeater’s
input frequency, that means you can hear
it without the repeater. If so, chances
are good the two of you can move to
another frequency and work simplex.
HOWEVER, you should never work simplex on
any of the frequencies reserved for
repeater inputs or outputs. This could
cause harmful interference to repeater
users. Always move to one of the
available simplex frequencies.
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T5C11
What is the term for a series of
repeaters that can be connected to
one another to provide users with a
wider coverage?
A.
B.
C.
D.
Open repeater system
Closed repeater system
Linked repeater system
Locked repeater system
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T5C11 Answer - C
When repeaters can be
connected together, they are
said to be “linked.” Linking
two or more repeaters allows
users to communicate reliably
over very long distances. This
is particularly useful for
emergency communications.
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T5C12
What is the main reason repeaters should
be approved by the local frequency
coordinator before being installed?
A. Coordination minimizes interference
between repeaters and makes the most
efficient use of available frequencies
B. Coordination is required by the FCC
C. Repeater manufacturers have exclusive
territories and you could be fined for
using the wrong equipment
D. Only coordinated systems will be approved
by the officers of the local radio club
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T5C12 Answer - A
There are only a limited number of
frequency pairs available for repeaters.
If two repeaters using the same pair are
too close together, they will interfere
with each other, and neither will be
particularly useful. The FCC does not
require that a repeater be coordinated
with others in the area, but if another
local repeater using the same frequency is
coordinated, the one not coordinated may
be required to cease interfering with the
coordinated repeater.
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T5C13
Which of the following statements
regarding use of repeaters is true?
A. All amateur radio operators have the
right to use any repeater at any time
B. Access to any repeater may be limited by
the repeater owner
C. Closed repeaters must be opened at the
request of any amateur wishing to use it
D. Open repeaters are required to use CTCSS
tones for access
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T5C13 Answer - B
A repeater costs a lot to
install and operate, and the
FCC allows the repeater owner
to limit access. If a user
abuses the repeater or breaks
the rules, that person may
lawfully be denied access to
the repeater.
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T5C14
What term is used to describe a
repeater when use is restricted
to the members of a club or
group?
A.
B.
C.
D.
A beacon station
An open repeater
A auxiliary station
A closed repeater
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T5C14 Answer - D
A closed repeater may only be
used by a certain group of
people, usually a club or group
that spent the money to get it
up and running. Most amateur
repeaters are open for use by
any licensed amateur, but the
FCC allows repeaters to be
closed if the owner or owners
so desire.
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Group T5D
Group T5D covers recognition and correction
of common station problems, symptoms of
overload and overdrive, distortion, over and
under modulation, RF feedback, off frequency
signals, fading and noise, and problems with
digital communications links.
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Fundamental Overload in a
Receiver
In reference to a receiver,
“fundamental overload” means
interference caused by very strong
signals from a nearby source. This
often happens when you have a
transmitter close by. In fact, you
may have experienced this with a car
radio when you passed a nearby
broadcast antenna. You can
sometimes here this station all over
the dial.
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Radio Frequency
Interference (RFI)
There are a number of sources of radio
frequency interference, including:
Fundamental overload – caused by a strong signal
source too close to the receiver
Spurious emissions – signals generated by a poorly
designed or poorly operated transmitter that are
close to, but not exactly on the transmit
frequency
Harmonics – multiples of a transmit frequency that
may be generated by a poorly designed or poorly
operated transmitter
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More About Radio Frequency
Interference (RFI)
Radio frequencies may interfere
with several types of consumer
electronics. Every ham should
insure that all station equipment is
operating properly to avoid this as
much as possible. However,
interference is often due to the
consumer electronics and not the ham
gear. Let’s look as some possible
problems.
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Telephone Interference
Sometimes a nearby transmitter
will cause interference to a
telephone. The most likely cause of
telephone interference from a nearby
transmitter is that the
transmitter's signals are causing
the telephone to act like a radio
receiver. This is most likely to
occur with poorly designed phones.
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Curing Telephone
Interference
Assuming that the amateur
equipment is working properly, the
logical first step in attempting to
cure a radio frequency interference
(RFI) problem in a nearby telephone
is to install an RF filter at the
telephone. The RF filter should
block any stray RF coming from the
transmitter through the phone lines
from entering into the phone.
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Television Interference
(TVI)
You may have someone to complain to you
that your equipment is causing
interference to their television. The
first thing you should do if someone tells
you that your transmissions are
interfering with their TV reception is to
make sure that your station is operating
properly and that it does not cause
interference to your own television. If
your equipment does not interfere with
your own TV, chances are good that your
equipment is not the problem.
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Curing RFI
If a television, radio receiver, telephone or other
equipment is experiencing interference when you operate, then
the problem needs to be corrected. You might want to try one
of the following:
Snap-on ferrite chokes
power cords going into
the name implies, they
the equipment to cause
– these are placed on telephone lines or
equipment experiencing a problem. As
“choke” the RF before it can get inside
interference.
Low-pass and high-pass filters – these filter our RF above or
below a certain frequency. Some are designed to be placed
between the transmitter and antenna, while others are installed
on the equipment being interfered with.
Notch and band-pass filters – these allow only a certain band
or range of frequencies to pass into a receiver. If the
receiver is receiving interference from frequencies outside of
this band or notch, this filter will block them.
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Interference? Check Your
Station!
When a neighbor reports that your radio
signals are interfering with something in his
home, the first thing you should do is check your
station and make sure it meets the standards of
good amateur practice.
If the interference is present while your
transmitter is not operating, then you are
definitely not the source of the problem. There
are many other devices that may cause
interference, including computers, fluorescent
lights, dimmer switches, and a whole host of
appliances. It helps if you can rule your station
out as the culprit.
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Part 15 Devices
Many consumer items generate radio
frequency energy when they operate. One
common RF generator is a computer.
Consumer items that generate RF energy are
generally registered with the FCC as “Part
15” devices. These devices must tolerate
interference from lawfully licensed
services, such as amateur radio, and they
may not interfere with the licensed
service. These items are usually
identified with a label that says they are
Part 15 devices.
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Dealing Part 15
Interference
If a "Part 15" device in your neighbor's home
is causing harmful interference to your amateur
station there are several actions you should take:
Work with your neighbor to identify the offending
device.
Politely inform your neighbor about the rules that
require him to stop using the device if it causes
interference. This requires lots of tact!
Above all, check your station to make sure it
meets the standards of good amateur practice.
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Alternator Noise
The alternator on a car can generate a
“whining” noise that that may be heard on
your receiver, and may also be heard by
others on your transmitter. If another
operator tells you he is hearing a
variable high-pitched whine on the signals
from your mobile transmitter, the first
thing you should suspect is that the power
wiring for your radio is picking up noise
from the vehicle's electrical system. The
source of that noise is often the car’s
alternator.
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Single Sideband Operations
Single sideband (SSB) is voice
mode that uses less bandwidth than
AM or FM. We’ll learn a little bit
more about exactly what it is later.
For now, you need to know that if
another operator reports that your
SSB signal is very garbled and
breaks up, the cause might be stray
RF energy getting into the
microphone circuit and causing
feedback.
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Problems Working the
Repeater
If you receive a report that your signal
through the repeater is distorted or weak, it
could be caused by one of several problems:
Your transmitter may be slightly off frequency –
check your frequency display to make sure your
frequency is exactly where it’s supposed to be.
Your batteries may be running low – this will
often show up as a weak or distorted signal.
You could be in a bad location – this might be
under an overpass, or the line of sight to a
building could be blocked by a large building.
The fix is usually simple.
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Digital Signal Processing
One of the best things to happen to
radio in a long time is digital signal
processing. When you speak into a radio
equipped with digital signal processing,
the processor turns your voice into a
series of zeros and ones. When these are
transmitted to a radio equipped to decode
them on the other end, your voice comes
out sounding much more lifelike and with
much less background interference. The
main reason for using digital signals
instead of traditional analog signals to
communicate is that digital systems can
automatically correct many errors caused
by noise and interference.
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Check-Up Time!
Now let’s try the questions from
this group.
You should make a note of any that
you miss for later review.
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T5D01
What is meant by fundamental
overload in reference to a receiver?
A. Too much voltage from the power
supply
B. Too much current from the power
supply
C. Interference caused by very strong
signals from a nearby source
D. Interference caused by turning the
volume up too high
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T5D01 Answer - C
If a transmitter operating on the
same frequency as your receiver is
close by, the radio frequency (RF)
energy of that source may be so
great that it overloads the
receiver. When this happens, the
receiver is unusable while the
signal is present. If the signal is
strong enough, it could cause damage
to the receiver.
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T5D02
Which of the following is NOT a
cause of radio frequency
interference?
A.
B.
C.
D.
Fundamental overload
Doppler shift
Spurious emissions
Harmonics
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T5D02 Answer - B
Strong signals on the
fundamental frequency, strong
harmonics of that frequency, or
spurious emissions may all
cause radio frequency (RF)
interference in a receiver.
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T5D03
What is the most likely cause of
telephone interference from a nearby
transmitter?
A. Harmonics from the transmitter
B. The transmitter's signals are
causing the telephone to act like
a radio receiver
C. Poor station grounding
D. Improper transmitter adjustment
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T5D03 Answer - B
Transmitters may cause
interference to nearby
telephones, PA systems, stereo
amplifiers and other types of
electronic equipment. Often,
the voice being transmitted may
be heard through such
equipment.
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T5D04
What is a logical first step when
attempting to cure a radio frequency
interference problem in a nearby
telephone?
A. Install a low-pass filter at the
transmitter
B. Install a high-pass filter at the
transmitter
C. Install an RF filter at the telephone
D. Improve station grounding
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T5D04 Answer - C
When a telephone is
experiencing radio frequency
(RF) interference, it can
usually be eliminated by
installing an RF filter on the
telephone to eliminate the RF
before it can enter the phone's
electronics.
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T5D05
What should you do first if someone tells you that
your transmissions are interfering with their TV
reception?
A. Make sure that your station is operating properly
and that it does not cause interference to your
own television
B. Immediately turn off your transmitter and contact
the nearest FCC office for assistance
C. Tell them that your license gives you the right
to transmit and nothing can be done to reduce the
interference
D. Continue operating normally because your
equipment cannot possibly cause any interference
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T5D05 Answer - A
If your transmissions do not interfere
with transmissions in your own home,
chances are good that they are not the
source of the problem for a television
outside of your home. BUT NOTE - a poorly
designed TV may be particularly sensitive
to interference. If so, while the FCC
will not hold you responsible if your
station is being operated in accordance
with its standards, you should try to
assist the other person in solving the
problem if at all possible.
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T5D07
Which of the following may be useful
in correcting a radio frequency
interference problem?
A.
B.
C.
D.
Snap-on ferrite chokes
Low-pass and high-pass filters
Notch and band-pass filters
All of these answers are correct
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T5D07 Answer - D
Each of these devices may be
used to filter radio frequency
(RF) interference before it can
reach the device experiencing
interference.
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T5D08
What is the proper course of action to
take when a neighbor reports that your
radio signals are interfering with
something in his home?
A. You are not required to do anything
B. Contact the FCC to see if other
interference reports have been filed
C. Check your station and make sure it meets
the standards of good amateur practice
D. Change your antenna polarization from
vertical to horizontal
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T5D08 Answer - C
When you receive a report of
suspected interference by your
station, the first thing you
should do is to check your
station to make sure it is
within technical standards. If
it is not, fix it.
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T5D09
What should you do if a "Part 15" device
in your neighbor's home is causing harmful
interference to your amateur station?
A. Work with your neighbor to identify the
offending device
B. Politely inform your neighbor about the
rules that require him to stop using the
device if it causes interference
C. Check your station and make sure it meets
the standards of good amateur practice
D. All of these answers are correct
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T5D09 Answer - D
"Part 15" devices are generators
of RF energy that can cause
interference. If they actually
cause interference, the owner must
stop using them. As an amateur, you
should insure that the problem is
not with your station and work with
your neighbor to isolate and resolve
the problem, as well as inform them
of their obligation with respect to
Part 15 devices.
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T5D10
What could be happening if another
operator tells you he is hearing a
variable high-pitched whine on the signals
from your mobile transmitter?
A. Your microphone is picking up noise from
an open window
B. You have the volume on your receiver set
too high
C. You need to adjust your squelch control
D. The power wiring for your radio is
picking up noise from the vehicle's
electrical system
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T5D10 Answer - D
The "whine" is likely to be
caused by your car's alternator
as it generates electricity.
It generates a signal that can
leak into your transmitter
without proper filtering.
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T5D11
What may be the problem if another
operator reports that your SSB signal is
very garbled and breaks up?
A. You have the noise limiter turned on
B. The transmitter is too hot and needs to
cool off
C. RF energy may be getting into the
microphone circuit and causing feedback
D. You are operating on lower sideband
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T5D11 Answer - C
Answer C is most correct. It
is possible, if you are using a
really old separate transmitter
and receiver, that you could
have your transmitter switched
onto the opposite sideband of
the other station, but the
opposite sideband could be
either upper or lower, so D is
not correct.
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T5D12
What might be the problem if you
receive a report that your signal
through the repeater is distorted or
weak?
A. Your transmitter may be slightly
off frequency
B. Your batteries may be running low
C. You could be in a bad location
D. All of these answers are correct
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T5D12 Answer - D
If you are operating with
batteries, the first thing to check
is whether the batteries are getting
weak. Also, not all locations will
get into the repeater equally well.
Finally, if the batteries are
charged, and you know you are in a
good location, check to see whether
you are on frequency.
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T5D13
What is one of the reasons to use digital
signals instead of analog signals to
communicate with another station?
A. Digital systems are less expensive than
analog systems
B. Many digital systems can automatically
correct errors caused by noise and
interference
C. Digital modulation circuits are much less
complicated than any other types
D. All digital signals allow higher transmit
power levels
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T5D13 Answer - B
Digital equipment is designed
to detect and correct errors
due to interference. This
usually means a clearer signal
in the receiver.
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Five Down, Five to Go!
You’re Halfway There!
This concludes Study Guide # 3.
Once you are satisfied that you can answer
80% of the questions in this Sub-element, you
are ready to move on to Study Guide # 4.
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