Accelerated Technician ClassAccelerated Technician Class

Session #3Session #3

Circuit ComponentsCircuit Components

The stuff radios are The stuff radios are made of.made of.

Right: Scorpion Antenna goes Right: Scorpion Antenna goes with the “Go Kit”with the “Go Kit”

ResistorsResistors

AA

++

--

4 4 ohmsohms

12 12 voltsvolts

As we have seen, resistors limit the flow of current.As we have seen, resistors limit the flow of current.

3 Amps3 Amps

Adding Resistors in SeriesAdding Resistors in Series

RRtt = R = R11 + R + R22 + R + R33 + … + + … + RRnn

Adding Resistors in ParallelAdding Resistors in Parallel

RR11 + + RR22

11

RR11

++ 11

RR22

++11

RR33

++ ……11

RR11 x x RR22RRt t ==

If only 2 resistors:If only 2 resistors:

RRt t ==

If all resistors are equal:If all resistors are equal:

RRt t = R / n= R / n

++11

RRnn

ResistorsResistors

ResistorsResistors

Resistor SummaryResistor Summary

Resistors oppose (resist) the flow of Resistors oppose (resist) the flow of current.current.

Resistors add in series, “reciprocal of Resistors add in series, “reciprocal of sum of reciprocals” in parallel.sum of reciprocals” in parallel.

Resistors vary in size and material Resistors vary in size and material according to heat dissipation.according to heat dissipation.

The unit of measurement is the Ohm The unit of measurement is the Ohm ((ΩΩ).).

DC and ACDC and AC

Direct Direct CurrentCurrent

Alternating Alternating CurrentCurrent

A Word about MagnetsA Word about Magnets

Remember:Remember:

1. Like charges repel and1. Like charges repel and opposite charges attractopposite charges attract

2. We can induce a current2. We can induce a current in a conductor passingin a conductor passing through a magneticthrough a magnetic field.field.

InductorsInductors

InductorsInductorsAnytime current flowsAnytime current flowsthrough a conductor,through a conductor,a magnetic field isa magnetic field iscreated around thatcreated around thatconductor.conductor.

InductorsInductorsIf we form the conductorIf we form the conductorinto a coil shape, we caninto a coil shape, we cangreatly intensify the greatly intensify the strength of the magneticstrength of the magneticfield.field.

We can store energy We can store energy in this magnetic field.in this magnetic field.

InductorsInductors

When we close the switch,When we close the switch,current flows through thecurrent flows through theinductor, building ainductor, building amagnetic field.magnetic field.

When we open the switch,When we open the switch,the field collapses, inducingthe field collapses, inducinga current in the inductor.a current in the inductor.

InductorsInductors

The value of an inductor can be varied by:The value of an inductor can be varied by:

Coil SpacingCoil Spacing

Coil DiameterCoil Diameter

Number of TurnsNumber of Turns

Core MaterialCore Material

The unit of measurement is the Henry (H).The unit of measurement is the Henry (H).

Adding InductorsAdding Inductors

In Series circuits:In Series circuits:

LLtt = L = L11 + L + L22 + L + L33……

In Parallel circuits:In Parallel circuits:

LLtt = = LL11 x L x L22

LL11 + + LL22

Inductor SummaryInductor Summary

Inductors store electrical energy in Inductors store electrical energy in their magnetic fields.their magnetic fields.Inductors are additive in series, Inductors are additive in series, “reciprocal of sum of reciprocals” in “reciprocal of sum of reciprocals” in parallel.parallel.Inductors tend to pass DC currents Inductors tend to pass DC currents and block AC currents.and block AC currents.The unit of measurement for inductors The unit of measurement for inductors is the Henry (H).is the Henry (H).

CapacitorsCapacitors

CapacitorsCapacitors A capacitor is made byA capacitor is made byseparating two conductiveseparating two conductiveplates by an insulator orplates by an insulator ordielectric.dielectric.

Capacitors store electricalCapacitors store electricalenergy in an electrostaticenergy in an electrostaticfield.field.

Capacitors tend to blockCapacitors tend to blockDC and pass ACDC and pass AC

CapacitorsCapacitorsRemember: Like Remember: Like chargeschargesrepel. Current will flowrepel. Current will flowonly until one plate isonly until one plate isfull of negatively full of negatively chargedchargedelectrons the other electrons the other hashasalmost none. This almost none. This createscreatesa difference of a difference of potentialpotential(a voltage) across the (a voltage) across the plates almost like a plates almost like a battery.battery.

WARNINGWARNING!WARNINGWARNING!

CAPACITORS CAN HOLDCAPACITORS CAN HOLD

A CHARGEA CHARGE

FOR QUITE SOME TIME.FOR QUITE SOME TIME.

TheyThey would be very happy to bite you.would be very happy to bite you.

CapacitorsCapacitors

The Value of a capacitor can be varied by:The Value of a capacitor can be varied by:

Increasing/decreasing the plate areaIncreasing/decreasing the plate area

Increasing/decreasing the plate spacingIncreasing/decreasing the plate spacing

Changing type of dielectric materialChanging type of dielectric material

The unit of measurement is the Farad (F).The unit of measurement is the Farad (F).

Adding CapacitorsAdding CapacitorsCapacitors add in parallelCapacitors add in parallel

CCtt = C = C11 + C + C22 + C + C33……

In SeriesIn Series

CCtt = = CC11 x C x C22

Note: Note: This is backwards fromThis is backwards fromresistors and inductors!resistors and inductors!

CC11 + C + C22

Capacitor SummaryCapacitor Summary

Capacitors store electrical energy in Capacitors store electrical energy in their electrostatic fields.their electrostatic fields.Capacitors are additive in parallel, Capacitors are additive in parallel, “reciprocal of sum of reciprocals” in “reciprocal of sum of reciprocals” in series.series.Capacitors tend to pass AC currents Capacitors tend to pass AC currents and block DC currents.and block DC currents.The unit of measurement for The unit of measurement for capacitors is the Farad (F).capacitors is the Farad (F).

The FuseThe Fuse

FuseFuse

The FuseThe FuseA fuse will self destruct when current flow A fuse will self destruct when current flow exceeds the fuse rating. This results in an open exceeds the fuse rating. This results in an open condition, and current flow will then cease, saving condition, and current flow will then cease, saving equipment from overheating and possible fire equipment from overheating and possible fire damage.damage.

What electrical component is used to protect other circuit components from current overloads?

A. FuseB. CapacitorC. ShieldD. Inductor

What type of component is often used as an adjustable volume control?

A. Fixed resistorB. Power resistorC. PotentiometerD. Transformer

What is the approximate amount of change, measured in decibels (dB), of a power increase from 5 watts to 10 watts?

A. 2 dBB. 3 dBC. 5 dBD. 10 dB

What electrical component stores energy in an electric field?

A. ResistorB. CapacitorC. InductorD. Diode

Intermission

Practical CircuitsPractical CircuitsPutting it all Putting it all

together.together.

FiltersFiltersWe have learned:We have learned:

Capacitors tend to pass AC and high Capacitors tend to pass AC and high frequenciesfrequencies

Inductors tend to pass DC and low frequenciesInductors tend to pass DC and low frequencies

We can now build circuits that…We can now build circuits that…Block transmission of harmonic radiationBlock transmission of harmonic radiation

Block reception of amateur frequenciesBlock reception of amateur frequencies

Pass only a desired group of frequenciesPass only a desired group of frequencies

Note the output of each type of filter.Note the output of each type of filter.

What instrument other than an SWR meter could you use to determine if a feedline and antenna are properly matched?

A. VoltmeterB. OhmmeterC. Iambic pentameterD. Directional wattmeter

Why is coaxial cable used more often than any other feedline for amateur radio antenna systems?

A. It is easy to use and requires few special installation considerationsB. It has less loss than any other type of feedlineC. It can handle more power than any other type of feedlineD. It is less expensive than any other types of feedline

11 22 33

If figure T5 represents a transceiver in which block 1 is the transmitter portion and block 3 is the receiver portion, what is the function of block 2?

A. A balanced modulatorB. A transmit-receive switchC. A power amplifierD. A high-pass filter

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. Low-pass filterB. High-pass filterC. Band-pass filterD. Band-reject filter

What is the function of a product detector?

A. Detect phase modulated signalsB. Demodulate FM signalsC. Detect CW and SSB signalsD. Combine speech and RF signals

Signals and EmissionsSignals and EmissionsAM/FM, SSB,

CWAlphabet

Soup!

Right: W4ZH J. Smith in New Orleans testing HF

Voice and HF Email

FCC Emission TypesFCC Emission Types

CWCW

DataData

PhonePhone

TestTest

MCWMCW

RTTYRTTY

ImageImage

PulsePulse

SS (Spread SS (Spread Spectrum)Spectrum)

CWCWIn CW theIn CW thetelegraph keytelegraph keysimply turnssimply turnsthe radiothe radiotransmittertransmitteron and off toon and off toform the form the MorseMorsecode code characterscharacters

CW and MCWCW and MCW

CW (continuous wave) is the on-off CW (continuous wave) is the on-off keying of a radio signal generally keying of a radio signal generally used for Morse codeused for Morse code

MCW is the tone modulation of a MCW is the tone modulation of a carrier wave made to sound like carrier wave made to sound like Morse code, as in the automatic Morse code, as in the automatic identifiers used on some repeaters.identifiers used on some repeaters.

PhonePhone

Phone is any voice transmissionPhone is any voice transmission

This includesThis includesAM (amplitude modulation)AM (amplitude modulation)

SSB (single side band, similar to AM)SSB (single side band, similar to AM)

FM (frequency modulation)FM (frequency modulation)

Amplitude ModulationAmplitude Modulation

An unmodulated RFAn unmodulated RFcarrier wavecarrier wave

A carrier wave AMA carrier wave AMmodulated with amodulated with asimple audio tonesimple audio tone

AM and SSBAM and SSB

An unmodulated RFAn unmodulated RFcarrier requires narrowcarrier requires narrowbandwidthbandwidth

Modulation of the Modulation of the carriercarriercreates sidebands. creates sidebands. ThisThisrequires more requires more bandwidth.bandwidth.Transmitter power is Transmitter power is spread across this spread across this bandwidthbandwidth

AM and SSBAM and SSB

The carrier contains noThe carrier contains noaudio information.audio information.

The sidebands containThe sidebands containduplicate audio duplicate audio informationinformation

By filtering out the carrier and one sideband,By filtering out the carrier and one sideband,we save spectrum and concentrate our RFwe save spectrum and concentrate our RFenergy into a narrower bandwidth. SSB isenergy into a narrower bandwidth. SSB istherefore more efficient.therefore more efficient.

SSBSSB

What type of receiver is shown in Figure T6?

A. Direct conversionB. Super-regenerativeC. Single-conversion superheterodyneD. Dual-conversion superheterodyne

Figure T6

MIXER INTERMEDIATE

FREQUENCY AMPLIFIER

1 AUDIO AMPLIFIER

OSCILLATOR BEAT FREQUENCY OSCILLATOR

AMAM vs.vs. SSBSSB

Sounds really niceSounds really nice

InexpensiveInexpensive

Simpler Simpler equipmentequipment

More efficient.More efficient.

Further range based Further range based on same output on same output power.power.

Narrower bandwidth, Narrower bandwidth, more room on more room on crowded bands.crowded bands.

All modern HF radios All modern HF radios support SSB (not all support SSB (not all support AM)support AM)

AM and SSBAM and SSB

When SSB is not modulated (when When SSB is not modulated (when you are not talking) the transmitter you are not talking) the transmitter output power drops to almost output power drops to almost nothing. nothing.

When either AM or SSB is over-When either AM or SSB is over-modulated the signal may cause modulated the signal may cause “splatter,” and interfere with other “splatter,” and interfere with other stations.stations.

Frequency ModulationFrequency Modulation

Unmodulated carrier, full powerUnmodulated carrier, full powerat all timesat all times

Waveform of modulatingWaveform of modulatingsignalsignal

Modulated carrier withModulated carrier withfrequency deviation andfrequency deviation andconstant amplitudeconstant amplitude

Frequency ModulationFrequency Modulation

FM transmitters operate at full power FM transmitters operate at full power at all times, even when you are not at all times, even when you are not talking.talking.

When an FM transmitter over-When an FM transmitter over-modulates, the transmitted signal modulates, the transmitted signal becomes so wide (bandwidth) it may becomes so wide (bandwidth) it may interfere with adjacent channels. interfere with adjacent channels. This is called over-deviation.This is called over-deviation.

ImageImage

Image transmissions include all Image transmissions include all modes that will produce a picture, modes that will produce a picture, either video or paper copy (like a either video or paper copy (like a FAX) at the receiver.FAX) at the receiver.These modes include:These modes include:

SSTV (slow scan television)SSTV (slow scan television)ATV (amateur television)ATV (amateur television)FAX (facsimile)FAX (facsimile)

ImageImage

A sample amateur SSTV transmission.A sample amateur SSTV transmission.

ImageImageAmateurs like toAmateurs like toreceive weatherreceive weatherimages direct fromimages direct fromthe satellites.the satellites.

The equipment isThe equipment isinexpensive and youinexpensive and youdon’t even need adon’t even need alicense!license!

Questions?Questions?