Download week 9 - Reocities

Class 9
et198B
ET 198B
Commercial and Amateur (Ham)
Radio
FCC license Preparation Course.
Bill Croghan
WB0KSW
PG-15-6818
Meters
• D’Arsonval movements – an electromagnet that
moves a needle.
• Thermo couple – a expandable mechanism that
moves a needle
• Digital – a device which converts a voltage into a
digital representation
• Multi meter – a device that switches the inputs to
various circuits so many thing can be displayed
on the same meter face.
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Voltmeter
• Measures the Electro motive force
ACROSS a component.
• Always placed in parallel with the device
being measured.
• Be sure that the range is adequate for the
expected voltage. Resistors in series with
the meter movement.
• AC meters are usually just DC meters with
a rectifier.
AMMETER
• Measure current through a circuit.
• Must always be in series with that circuit.
• Should be very low impedance so as not to
change the circuit in which it is inserted.
• Range is critical.
• Shunts are sometimes used to increase the
range of a small meter. The shunt is a parallel
circuit that carries a percentage of the current.
• CAUTION Always be sure that you are in series
and not in parallel!
OHMMETER
• Usually just an ammeter in series with a
battery.
• Must be used without power applied to the
circuit.
• Component being tested should not be
part of the circuit. Lift at least one end.
• Higher resistance ranges have more
battery voltage. Be careful you do not
damage components.
Some practical circuits
• Draw a series parallel circuit. Show where
the voltmeter would be placed. Show
where the ammeter would be placed.
Show how a resistance reading would be
taken.
• Try numerous circuits.
Multi Meter.
• Show examples.
• Explain how different plug holes are used
for current and current ranges.
• Demonstrate ohmmeter and beeping
continuity checker.
• Show transistor checker.
• Show other ranges.
S- METER
• Receiver Signal Strength meter.
• Usually marked in units 1-9, then plus
10,20,30,40 DB.
• Units likely have no real meaning, but are
merely representative. May be accurate
as relative db readings, but probably not
anything else.
• Show FIM
PEAK Reading, RMS, Average
• Explain the difference
• Show relationship between
– Peak
– Peak to peak
– RMS
– Average
RF watt meter
• Might be peak, average or PEP.
• May be used to show forward and
reflected.
• Might have an SWR scale, or may have to
use a nomagraph or calculate.
• Sensitive to frequency.
Building or Modifying equipment
• As an amateur, you are authorized to modify
your own equipment.
• Start simple. Solder plugs, mic connectors,
audio cables.
• Try kits. Follow directions.
• Internet has tons of Mods for many radios.
• CAUTION IF you modify a radio to work out
side of the Ham bands, DO NOT TRANSMIT.
Most ham radios are not authorized on
commercial frequencies.
• You are not authorized on non Ham frequencies.
SOLDERING
• Discuss soldering vs. welding, twisting, wire
wrap etc.
• Emphasize heat the components, then melt the
solder to the component.
• Do not melt the solder to the iron and let it drip
onto the component.
• “cold solder joint”
• Shiny and solid.
• Use appropriate iron.
• ventilation, safety glasses, fire danger
Other Test instruments
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Frequency counter
Oscilloscope
Spectrum analyzer
Signal generator
Signal tracer
Antenna analyzer
SWR meter
Repeaters
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Purpose – To extend the range of your radios
Procedures – listen before transmitting
Wait for courtesy beep.
Avoid long discussions during busy times.
To break in, give your call sign during a break.
Short transmissions give others a chance,
especially if they have an emergency.
• “BREAK BREAK” usually reserved for an
emergency or urgency.
• “Is this frequency in use?”
Repeaters cont
• Subaudible tones A continuous tone between
60 and 300 Hz that must be present to access a
repeater.
• Also known as PL, private line, quiet channel,
tone access. CTCS (continuous Tone Coded
Squelch)
• Other systems include tone burst, and digital
private line.
• Crossband repeaters. Receive transmissions on
one band, retransmit on another.
Repeaters cont
• Know the frequency, tone (if any) and
offset.
• 144 MHz, offset usually 600 KHz
– 144-146, input of repeater is lower
– 147 Input is usually higher
• 70 cm Offset usually 5 MHz
– Offset is usually 5 MHz. In this area, input is
usually lower, but some areas differ.
Repeaters cont
• Morse code is usually used for ID, but may
also have other information.
• Morse ID’s usually at 20 wpm
• Voice ID’s are also used. Polite Id’er only
transmits during breaks. If normally voice,
it may do Morse during voice over.
• Use the repeater ID to remind you to ID.
IF you did not hear it, it may have
happened while you were talking.
Simplex
• Two way communications with out
repeaters. One frequency.
• Common Simplex 2 meters 146.52
• Common Simples 70 cm 446.000
• Calling frequency vs. working frequency.
• Should use simplex whenever practical.
• If talking on a repeater, listen on the input
to see if simplex is possible. Many radios
have a reverse button.
Repeater Coordination
• Repeater Frequencies are a limited resource in major
population areas.
• Volunteer coordinators proved guidance.
• You are responsible for finding a frequency, not the
coordinator.
• The coordinator needs to know what frequency, location
power, type antennas, sub audible tones.
• The coordinator may recommend you not use that
freq/location/tone
• If you do not follow the coordinator, you are responsible
for any interference.
Frequency Coordinators cont
• The repeater coordinator may deny
because of interference, others already
using that frequency or others who are
going to use that frequency.
• Repeaters do not own the frequency, but
coordinated repeaters have priority.
Special modes
• Beacons – transmission for the
observations of propagation and/or
reception. Might be from a balloon, hidden
transmitter, or other devices.
• Beacons must still ID, but may be in
automatic operation.
• Maximum Beacon power is 100 watts.
• Beacons are or may be one way
transmissions
EME
• Earth Moon Earth. Also called moon
bounce.
• Typically CW. Rare SSB
• Requires tremendous antennas with high
gain on both TX and RX.
• The moon must be visible.
• Antennas are often “bore sighted” with TV
cameras.
Satellites
• Any class of Ham may use the satellites
• The satellites are not Geostationary.
• As the satellite approaches, Doppler shift
cause the frequency to be higher.
• As the Satellite recedes, the Doppler
makes the frequency lower.
• Apogee is the most distance point from
earth
• Perigee is the closest distance from earth.
International Space Station
• Most if not all of the astronauts are Hams.
• They operate during their free time
• The space station is in orbit and you will only
have 4-6 minutes per pass to communicate.
• They may have many different listening
frequencies but usually only one transmit
frequency.
• The schedules and frequencies are published in
QST magazine.
Telecommand
• A one way transmission to initiate, modify or
terminate functions of a remote device.
• Control of model boats, airplanes, cars etc.
• Control of repeaters, beacons, coffee pots, etc.
• Transmitter must be labeled with call sign and
the station licensee’s name and address.
• Specific frequencies are recommended and
coordinated for large meets and club get
together
Telecommand cont.
• For non- model control.
• Must have a wireline or radio control link.
• A photocopy of the station license must be
posted in a conspicuous place
• The station must be protected do
unauthorized transmissions may not be
made.
Autopatch
• A device that allows amateurs to connect with the
commercial telephone system.
• May be part of a repeater, or a simplex patch.
• Somebody is paying the phone bill.
• Careful to let the other party know they are on the radio.
• The usual rules about commercial use, bad language
and id’s apply.
• If you get put on hold and there is music on hold, hang
Up!
• Remember, the autopatch is not private. Don’t try
special codes, i.e. voice mail passwords.
• Some repeaters cover the tones with other things.
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Amateur TV