07 Cf351 f07 Superheterodyne Receiver

CF351 F07 - 1

Unclassified

4 Hour Conference, W/ 7Hr PE1

Safety & Environmental Impact is “LOW”

TIII:

CF351 F07 - 2

TIII: SUPERHETERODYNE RECEIVERSUPERHETERODYNE RECEIVER

Action:Given a schematic diagram, answer questions pertaining to Ckt

operation, Transmitter & Receiver group concepts and signal tracing procedures.

Condition: W/O References.

Standard: Answer 7 of 10 written questions correctly as well as troubleshoot & locate a malfunction W/in 20 minutes.

20 seconds

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All electronic communications both in defense as well as the private sector are centered around the very basic transmitter & receiver groups.

This lesson will concentrate on the Receiver group w/ an overview in a block diagram of the transmitter group.


Overview

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FMFM; Frequency Modulated

The FCC, Federal Communications Commission grants all License, & call letter designations. 3 call letter stations were grandfathered in due to there existence before the establishment of the FCC in 1932.

Transmitter Group


Overview;Overview;

WLWCincinnati

OH.

KLTPittsburg

Pa.AM AM ; Amplitude Modulated

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OSCILLATOR1000 KHZ CW

TRANSMITTER – Generates a continuous wave (CW) carrier frequency with an additional signal intelligence impressed upon it, thus becoming an Amplitude Modulated (AM) signal. Once powered up the AM signal is put on the air as transmission RF waves via an antenna.


TRANSMITTER GROUPTRANSMITTER GROUP; OSCILLATOROSCILLATOR

Modulator

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TRANSMITTER GROUPTRANSMITTER GROUP; MODULATORMODULATOR

A. Input acquired from OSCILLATOR (1000 KHZ) B. A 2nd signal from transducer is mixed with 1000 CW to

produce and Amplitude Modulated (AM) signal or Carrier Transmission.

Modulatoror

Mixer


TRANSDUCER{Microphone}

PWR Amp

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TRANSMITTER GROUPTRANSMITTER GROUP; POWER AMPLIFIERPOWER AMPLIFIER

HometownUSA

A. Power Amplifier Boosts the AM signal up and applies it to the Antenna.

B. The AM – RF energy is transferred to the atmosphere in the form of Radio Frequency (RF) radiation.

POWER AMPLIFIER

Modulatoror

Mixer


TRANSDUCER

Dear Ma

Dear Ma

Receiver

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RECEIVER GROUPRECEIVER GROUP; ANTENNAANTENNA

RF RADIATION

Antenna (aerial)

Is the device that intercepts the AM electromagnetic radiation waves. As

the waves pass and are cut by the aerial, small amounts of current

will be induced upon it.

HometownUSA

Tuner

USPS

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HometownUSA

ANTENNA

TUNER1000 KHZ

A: Selects one signal from the many on the aerial by tuning a Parallel LC Tank circuit to resonate @ 1000 KHZ.

B: The tuner is capable of tuning-in all the AM frequencies with in the AM spectrum of 540 KHZ – 1610 KHZ.

C: The selected frequency of 1000 KHZ is applied to the converter or mixer.


RECEIVER GROUPRECEIVER GROUP; TUNERTUNER

Tuner PC 38

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Tuner

O

Antenna

T3T2Q1

3

2

4

5

1

7

6

T1

R2

6.2 K

R1

47 K

R3

22 K

C3

.01 f

R4 1 K

C1 A

C1 B

TIII: SUPERHETERODYNE RECEIVER

RECEIVER GROUP; PC Antenna Antenna & TunerTuner.

PC 38

Local Osc

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PC 38, LO


RECEIVER GROUPRECEIVER GROUP; Local Oscillator [LO]Local Oscillator [LO]

CONVERTER or

MIXERLOCAL OSCILLATORLOCAL OSCILLATOR1455 KHZ

TUNER1000 KHZ

HometownUSA

1. The LO Signal output is always the Tuner Frequency, Plus 455 KHz Regardless of what AM signal is

tuned.2. It is tuned simultaneously with the RF Tuner.3. The output would be 1000 + 455 = 1455 KHZ CW.4. The output of 1455 KHZ is sent to the Converter or Mixer.

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Converter / Mixer


RECEIVER GROUPRECEIVER GROUP; Local Oscillator [LO] Local Oscillator [LO]

PC 38

Tuner

LO

OO

Antenna

T3T2T2Q1

33

22

44

55

11

77

66

T1

R2

6.2 K

R1

47 K

R3

22 K

C3

.01 f

R4 1 K

C1 A

C1 B

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PC 38, Mixer


RECEIVER GROUPRECEIVER GROUP; Converter / MixerConverter / Mixer

MaMaUSAUSA

The 1000 KHZ from the Tuner is heterodyned with a 2nd signal from the Local Oscillator [1455 KHz] to produce 4 different output frequencies.

F1RF

F2LO

F2+f1SUM

f2-f1 f2-f1 DIFFERENCEDIFFERENCE

1000 KHZ

1455 KHZ

2455 KHZ

455 KHZ

orCONVERTER

MIXER

RF TUNER1000 KHZ

LO1455 KHZ

INTERMEDIATEINTERMEDIATEFREQUENCYFREQUENCY

(IF)(IF)

HometownUSA

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IF Amp


RECEIVER GROUP; Converter / MixerConverter / Mixer

PC 38

Tuner

LO

Converter

O

Antenna

T3T2Q1

3

2

4

5

1

7

6

T1

R2

6.2 K

R1

47 K

R3

22 K

C3

.01 f

R4 1 K

C1 A

C1 B

455 KHz

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PC 39, IF Amps


RECEIVER GROUPRECEIVER GROUP; IF AmplifierIF Amplifier

IF amplifier has the most receiver gain and is made up of 2 cascaded high gain amplifiers tuned to 455 KHZ.

Sensitivity and bandwidth [T4 & 5] are determined by this stage.

The [IF] output is sent to the detector (demodulator).

IF Amplifier455 KHZ

orCONVERTER

MIXER

RF TUNER1000 KHZ

LO1455 KHZ

MaMaUSAUSA

PC 38

PC 39

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Detector


RECEIVER GROUP; IF AmplifiersIF Amplifiers

PC 39

T4 T5

Q2 Q3

R5

56 K

R7

10 K

R8

47 KC4

10 f

T3 s

Operate

Test

R 11 2.7 K

R 13 100 K

R 12 5 K

15

C 11 .0

5 f

D 1

1710 13

9 12

11 14

8

C6 10 f

11stst IF IF AmpAmp

2nd IF 2nd IF AmpAmp

DetectorO

C8

C7

R6 C9

C10R9 R10

38 card

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PC 39 Detector


RECEIVER GROUPRECEIVER GROUP; DETECTOR DETECTOR OR DEMODULATOR DEMODULATOR

Rectifies the modulated signal, then filters out the 455 KHz Leaving only the audio frequency or intelligence of 50 Hz – 20 KHzWhich is sent to the AF amplifiers.

Detector

IF amplifier455 KHZ AM

orCONVERTER

MIXER

RF TUNER1000 KHZ

LO1455 KHZ

MaMaUSAUSA

Your Favorite

Son

455 AM Rectified Filtered

PC 38 PC 39

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RECEIVER GROUP; DETECTORDETECTOR or DEMODULATORDEMODULATOR

PC 39

38 card

Filter

O

T4 T5

Q2 Q3

T3 s

Operate

Test

R 13 100 K

R 12 5 K

15

C 11 .0

5 f

D 1

Detector

1710 13

9 12

11 14

8

C6 10 f

1st IF Amp

2nd IF Amp

DetectorDetector

C4

10 f

R5

56 K

R7

10 K

R8

47 K R11 2.7 K

R6 C1 R9 C9 R10

C10

C8

AGC

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PC 39, AGC


RECEIVER GROUP; AVCAVC or AGCAGC

Automatic Volume Control or gain control is taken at the detector (demodulated and fed back to the first IF amplifier base. Required to overcome atmospheric and terrain conditions that adversely affect signal strength between the transmitter & receiver.

AVC or AGC

Detector

IF Amplifier455 KHZ AM

orCONVERTER

MIXER

RF TUNER1000 KHZ

LO1455 KHZ

PC 38 PC 39

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All Ckt PC 39


RECEIVER GROUP; AVC or AGCAVC or AGC

PC 39

R6 C1 R9 C9 R10

C10

C8

O

T4 T5

Q2 Q3

T3 s

Operate

Test

R 13 100 K

R 12 5 K

15

C 11 .0

5 f

D 1

AVC

AVC

1710 13

9 12

11 14

8

C6 10 f

1st IF Amp

2nd IF Amp

Detector

R5

56 K

R7

10 K

R8

47 KC4

10 fR 11 2.7 K

PC 38

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RECEIVER GROUP; 11stst & 2 2ndnd IF Amp, Detector, AVC IF Amp, Detector, AVC or AGC.AGC.

PC 39

38 card

Filter

O

T4 T5

Q2 Q3

T3 s

Operate

Test

R 13 100 K

R 12 5 K

15

C 11 .0

5 f

D 1

Detector

AVC

AVC

1710 13

9 12

11 14

8

C6 10 f

11stst IF IF AmpAmp

2nd IF 2nd IF AmpAmp

DetectorDetector

R5

56 K

R7

10 K

R8

47 KC4

10 fR 11 2.7 K

R6 C1 R9 C9 R10

C10

C8

PC 39

Audio Amps

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PC 40


RECEIVER GROUP; AUDIO AMPLIFIERAUDIO AMPLIFIER

AUDIO AmplifiersAUDIO Amplifiers

AVC OR AGC

Detector

IF Amplifier455 KHZ AM

orCONVERTER

MIXER

RF TUNER1000 KHZ

LO1455 KHZ

3 stages: Audio preamp Audio driver Audio push- pull

AUDIO AMPLIFIERAUDIO AMPLIFIER

PC 38 PC 39 PC 40

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Audio Pre Pre AmpAmp

Audio DriverDriver

Audio Push Push PullPull

Q4

Q5

Q6

Q7

18

2119

20

24

27

31

29

28 O

22

23

25

26

T6

T7

R18

C13

C14

R15

R14

R17

R16

C12

R20

R19

R21C15

D2 R2

5

R24

R23

C16

E

30


RECEIVER GROUP; AUDIO AMPLIFIERAUDIO AMPLIFIER

PC 40

Trouble Shoot

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RECEIVER GROUPRECEIVER GROUP; Trouble shooting procedure.Trouble shooting procedure.

2

4

3

18

20

19

21

23

22

27

31

26

24

25

29

9

11

10

12

14

13

15

PC38 PC39 PC40

Tone, PC 40 OK

Tone, PC 38, 39, 40 OK

Tone, PC 39, 38 OK

11stst

2nd2nd

3rd3rd

No TonePC 40

Malfunctioning

No TonePC 39

Malfunctioning

No TonePC 38

Malfunctioning

Lesson Test

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Answers 1-9


Review QuestionsReview Questions;

1. Where does heterodyning take place in the receiver taught? ________________

2. The IF amplifier is tuned to the __________ frequency of _______ KHz.

3. What are the block diagram stages of a Super heterodyne receiver?

___________ ___________ ____________

___________ ___________ ____________

___________ ___________

4. What components make up the Local Oscillator & Feedback? ___, ____, ____.

5. What is the propose of the AVC [AGC] Ckt in the receiver? ______________

6. What are the two actions needed to Demodulate an AM carrier?

_______________, _____________.

7. What type of coupling is used in the RF & IF section of the Super-Het-Receiver discussed in this lesson? _____________________

8. T6 Secondary in the audio amplifier is center tapped to provide 2 signals that are the ________ in amplitude and the ____________ in polarity.

9. What is the purpose of Q5 Driver Amp in PC 40? _____________________

CF351 F07 - 26

Answers 10- 21


Review QuestionsReview Questions;

10. What is the frequency range of a standard AM broadcast receiver? _____________

11. Frequency conversion can handled by two stages, or only one. What are they called? ____________ , ________________ .

12. After a receiver is properly aligned, it should have maximum _______ & ________

13. What is the frequency of the Local Osc, [LO] ? __________

14. What is the main use of the Audio output Transformer [T7] ? _________ _______

15. What section of a super heterodyne receiver provides the most gain? _____

16. Where & what is the first test in troubleshooting an inoperative receiver ? _____ , ____________ _______________

17. When troubleshooting the superhet receiver, which section [card] do you check first? _____________ ______

18. What is the purpose of Cr1 [D1] ? _________________ ______________

19. When aligning the super heterodyne receiver , Which section is aligned first ? ______________ ___ _______

20. What method of troubleshooting is used on the super heterodyne receiver ? _________ __________; _______ ________ ___________ .

21. There are four frequencies produced by heterodyning. What frequency is used by the super heterodyne receiver ? ___________________

CF351 F07 - 27

PE Set UP

PE Write UP


Lesson TestLesson Test;

Lesson Test:

Standard:

10 Questions W/in 20 Minutes.

70% Minimum Accuracy.

Reference: NONE

RF TUNER CONVERTER ORMIXER

IF AMPLIFIER DETECTOR

AF AMPLIFIER

SPEAKERSPEAKERLOCAL

OSCILLATOR

CF351 F07 - 28

PE Write UP


PE Write UpPE Write Up; Example 1.Example 1.

Card TP Indication Test Equip3939 TP 15TP 15 F-GenF-Gen

3939 TP 9TP 9 F-GenF-Gen


3838 TP 3TP 3 11.89 VDC11.89 VDC DMMDMM

3838 TP 2TP 2 280mVDC280mVDC DMMDMM3838 TP 4TP 4 280mVDC280mVDCDMMDMM3838 TP 2/4TP 2/4 0/0 0/0 DMMDMM

Card: 3838Circuit: LOLOComponent: Q1Q1Malfunction: ShortShort

CF351 F07 - 29

PE Set UP


PE Write UpPE Write Up; Example 2.Example 2.

Card TP Indication Test Equip3939 TP 15TP 15 F-GenF-Gen



3939 TP 10TP 10 12 VDC12 VDC DMMDMM

3939 TP 9TP 9 780mVDC780mVDC DMMDMM3939 TP 11TP 11 220mVDC220mVDCDMMDMM3939 TP 10/9TP 10/9 Hi/Hi Hi/Hi DMMDMM

Card: 3939Circuit: 11stst IF AMP IF AMPComponent: Q2Q2Malfunction: OpenOpen

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07 Cf351 f07 Superheterodyne Receiver