ECE 404L: RF ELECTRONICS LABORATORY DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING MICHIGAN STATE UNIVERSITY I. TITLE: Lab III - AM/FM Radio - AM Radio II. PURPOSE: This lab will focus on soldering and testing of the AM portion of the radio. The concepts covered are: 1. amplitude modulation (AM); 2. superhetrodyne receiver; 3. AM detector and automatic gain control (AGC); 4. Intermediate Frequency (IF) transformers; 5. IF amplifiers; 6. AM oscillator and mixer. The laboratory techniques covered are: 1. using the AM feature on the function generator; 2. troubleshooting by doing static measurements with a digital multimeter; 3. measuring gain, bandwidth and quality factor with a scope; 4. tuning. III. BACKGROUND MATERIAL: See Lab Lecture Notes. IV. EQUIPMENT REQUIRED: 1 Agilent 54833A Infiniium Oscilloscope 2 Agilent 1161A 10:1 Miniature Passive Probes 1 Agilent 33250A Function / Arbitrary Waveform Generator 1 Fluke 8840A Digital Multimeter 1 HP 6216C DC Power Supply 1 Soldering Station Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 1
V. PARTS REQUIRED: 1 Elenco Model AM/FM-108TK kit 1 9-Volt adapter plug 1 Sub-miniature phono plug 2 BNC-to-Banana adapters 1.001:F capacitor 1.02:F capacitor VI. LABORATORY PROCEDURE: A) AM Detector and Automatic Gain Control (AGC) Circuit 1. This is a two week lab. When time runs out for the first week, go to section I) which describes clean-up. Pick up where you left off the following week. 2. Get your Elenco AM/FM-108TK kit from the storage shelf. 3. Find and remove the parts listed on pages 15-16 of the Assembly and Instruction Manual. These are in your AM RADIO PARTS bag. We have found that some of the IF Cans (transformers) are defective. One quick way to test them is to take a resistance measurement. The turns ratio of a transformer is related to the thickness of the wire and its resistivity. Since both sides of the transformer are using the same thickness wire, we could measure the resistance of the primary and secondary and take their ratio. This will roughly be the same as the turns ratio. These resistances are very small and so we will need to do a 4-wire measurement. Locate the black dot AM IF Coil (T8). The primary side has three terminals. Measure and record in the Lab Report the resistance of the outer two terminals of the primary side. Then measure the resistance of the secondary windings which has two terminals. Record and calculate the resistance ratio as indicated in the Lab Report. This should be around 4.5. If your ratio is way off ask your instructor for another black dot transformer. Likewise measure the primary and secondary resistance of the yellow dot AM IF coil (T6). Record and calculate the resistance ratio. This should be around 30. If your ratio is way off ask your instructor for another yellow dot transformer. 4. Prepare your soldering iron for use. Do all soldering on the soldering tray. Please take turns soldering in the parts. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 2
Because you are handling solder which contains lead, please make sure you wash your hands with hot soapy water when you finish lab. If you are unsure about any instructions, please ask your instructor for help and/or view one of the assembled radios. 5. Complete the assembly instructions on pages 15-16 of the Assembly and Instruction Manual. B) Static Measurements of the AM Detector and AGC. 1. We will use the HP6216C power supply in place of the 9 volt battery. The HP6216C power supply is adjustable from a magnitude of 0 to 30V. Set the magnitude of the supply to approximately 9 volts and set the current limiter to approximately 25mA. Leave the meter in the current reading position. If you have forgotten how to do this, see Lab II. 2. Obtain a 9 volt battery adapter from your Parts Box. Do not connect this to the radio until instructed to do so. 3. Connect the BLACK wire of the battery adapter to the positive terminal of the power supply and the RED wire of the battery adapter to the negative terminal. Using a black banana wire, short the minus terminal of the power supply to the ground terminal of the power supply. 4. Turn OFF the power supply. Obtain a sub-miniature plug from the wall racks and connect the banana ends to a 10 S load mounted on a gray block. Plug the other end into the earphone jack on the printed circuit (pc) board. (This will make the following measurements less painful!) 5. Set the volume control on the radio to the OFF position (turned fully counter-clockwise). Connect the 9 volt adapter to the battery holder on the radio. Turn ON the power supply. The current meter should read zero. If not ask your instructor for help. 6. While watching the current meter on the power supply, turn the volume control of the radio to the ON position (rotate clockwise until a click is heard). The meter should read under 20 ma. If so, go to step 7. If this is not the case, turn off the power supply. Check for shorts or poor solder connections. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 3
Note: If your radio tries to draw more than 25mA of current then the voltage will collapse, that is, it will drop to a much lower value in voltage than what is set by the voltage control. Do not try to increase the current control setting because something is seriously wrong. Increasing the current control may melt some of the components in your radio. Please ask your instructor for help. 7. Connect the LO input of the Fluke 8840A DMM to the ground of the power supply. Using a grabber-to-banana wire on the positive HI input of the DMM, measure the power supply voltage at the emitter of Q13 and adjust if necessary to 9.0 volts. Make sure that the AM/FM switch is in the AM position. Measure the DC voltage at Test Point 5 (TP5) as shown in Fig. 13 on page 16 of the Assembly and Instruction Manual. This should be approximately 1.5 volts. Record in the Lab Report. If so, proceed to step 8. If this reading is off by more than 0.5 volts, turn off the power supply and check the polarity of D4. Also check that R36, R35 and T6 are installed correctly or ask your instructor for help. 8. Measure the DC voltage at TP3. This should be approximately 9 volts. If so, proceed to step 9. If not, turn off the power supply and check that T8 is installed correctly or ask your instructor for help. 9. Disconnect the grabber from TP3 and turn the volume control to the OFF position. C) Dynamic Measurements of the AM Detector and AGC. 1. To connect the function generator to the radio, we need to convert the BNC connector on the function generator to a banana connector. Place the BNC-to-Banana adaptor, found in the blue box on your lab bench, on the function generator output. Connect a black banana wire from the black terminal on the function generator to the black ground terminal on the power supply. Connect a grabber wire from the red terminal of the function generator to a 0.001:F capacitor from your Parts Box. Connect the banana plug of another grabber wire into an alligator clip from your blue box. Connect the alligator clip to the other side of the 0.001:F capacitor. Connect the remaining grabber end to TP3 as shown in Fig. 14 on page 17 of the Assembly and Instruction Manual. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 4
2. Turn ON the volume control and monitor the current of the power supply. It should still be less than 20 ma. Turn ON the function generator and set the frequency to 455 khz and 20 mv P-P (High Z). Measure the DC voltage at TP5 with the DMM. Increase the amplitude of the function generator until the voltage at TP5 just starts to drop by 10%. This point is called the AGC threshold with no IF gain. Record the setting of the amplitude of the function generator and the value of the DC voltage at TP5 in the Lab Report. 3. Turn ON the oscilloscope. If not already present, connect two 10:1 probes to your scope, one for channel Ø and one for channel Ù. Press the Default Setup button to clear the settings of the last user. We would like to display TP2 on channel Ø and the cathode (barred side) of D4 on channel Ù. Connect the ground clips to any grounded point on the pc board. 4. Leave the function generator set to 455 khz. Turn on the amplitude modulation option of the function generator by pressing the MOD button on the lower left side. The default is AM with a modulation index of 100%. Set the modulation index to 80% by highlighting AM Depth and the using the keypad to enter 80. 5. Set the frequency of modulation to 1 khz by highlighting AM Freq and the using the keypad enter 1 k. 6. Adjust the volume control until you hear the 1 khz tone in the small speaker. If this test succeeds, proceed to step 7. If this test fails, turn off the power supply and check the polarity of D4. Also check that R42 and TP5 are installed correctly or ask your instructor for help. 7. Set the volume control to minimum. Vary the amplitude of the function generator until the signal at TP2 is approximately 400 mv P-P. Do not use averaging otherwise you may not see the AM modulation. Do not use AC coupling otherwise you won t see the negative peak detector. You may want to use Bandwidth Limiting to lower the noise. This can be found by double clicking on the channel number. 8. Print these waveforms for each member of your group. Mark which waveform is which. Mark this section letter and number on the top right side of your plot and attach it as indicated in the Lab Report. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 5
9. Increase the modulation frequency until the voltage at TP2 drops to approximately 282.8 mv P-P or 0.707 times the value in step 7. This is the bandwidth of the AM detector and this frequency should be greater than 5 khz. Record the value in the Lab Report. 10. Print these waveforms for each member of your group. Mark which waveform is which. Mark this section letter and number on the top right side of your plot and attach it as indicated in the Lab Report. Notice the phase shift of the amplitude modulated signal and the AM detector. It should be around 45 at the corner frequency. 11. Turn OFF and disconnect the power supply. 12. Turn the Output of the function generator OFF and disconnect it from the radio. D) Second AM IF Amplifier 1. Find and remove the parts listed on page 19 of the Assembly and Instruction Manual. These are in your AM RADIO PARTS bag. Measure the primary and secondary resistance of the white dot AM IF coil (T7). Record in the Lab Report and calculate the resistance ratio. This should be around 30. If your ratio is way off ask your instructor for another white dot transformer. Complete the assembly instructions on page 19. 2. Reconnect the power supply and turn ON the power supply. Again monitor the current for problems. 3. Measure the DC voltage at the emitter of Q9. This should be approximately 1 volt. Record the value in the Lab Report. If so, proceed to step 4. If this reading is off by more than 0.5 volts, turn off the power supply and check that R39, R40, R41 and Q9 are installed correctly or ask your instructor for help. 4. Connect the function generator to TP4 through a 0.02:F capacitor from your Parts Box as shown in Fig. 18 on page 20 of the Assembly and Instruction Manual. Use banana-to-grabber wires and alligator clips to make this connection like that done in section VI-C. 5. Set the scope to AC coupling for both channels. Connect one channel to TP3 and the other to the base of Q9. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 6
6. Turn ON the function generator output and set the frequency to 455 khz and 20 mv P-P (High Z). Turn OFF the modulation. Increase the amplitude of the function generator until the voltage at TP3 is about 4 V P-P. 7. What we need to do next is make the amplifier resonate at 455 khz. We will do this by varying the inductance of the coil. Using a small screwdriver, adjust T8 so that the gain from TP4 to TP3 is maximized. Re-adjust the function generator s amplitude to maintain an approximate 4 V P-P signal at TP3. Re-adjust T8 slightly to verify that the gain is maximum. Repeat if necessary. 8. Once T8 is aligned, measure the peak-to-peak voltage at TP3 (which is the collector of Q9) and at the base of Q9. Record and calculate the gain of the 2nd IF Amplifier. It may be in the range of 100 to 300. 9. Print these waveforms for each member of your group. Mark which waveform is which. Mark this section letter and number on the top right side of your plot and attach it as indicated in the Lab Report. 10. Vary the frequency of the function generator and measure the upper and lower 3 db frequencies, that is, where the voltage at TP3 drops to 0.707 of its center frequency value or approximately 2.82 V P-P. Record. As a check, calculate f o as indicated in the Lab Report. It should be very close to 455 khz. If not, repeat the bandwidth measurements. Calculate the bandwidth and Q o as indicated in the Lab Report which may be around 20 khz and 25, respectively. 11. Turn OFF and disconnect the power supply. 12. Turn the Output of the function generator OFF and disconnect it from the radio. E) First AM IF Amplifier 1. Find and remove the parts listed on page 21 of the Assembly and Instruction Manual. These are in your AM RADIO PARTS bag. Complete the assembly instructions on page 21. 2. Reconnect the power supply and turn ON the power supply. Again monitor the current for problems. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 7
3. Measure the DC voltage at TP5. This should be approximately 1.5 volts. Record the value in the Lab Report. If so, proceed to step 4. If not, turn off the power supply and check that R37and Q8 are installed correctly or ask your instructor for help. 4. Measure the DC voltage at the emitter of Q8. This should be approximately 0.8 volts. Record the value in the Lab Report. 5. Connect the function generator to TP6 through a 0.001:F capacitor from your Parts Box as shown in Fig. 19 on page 22 of the Assembly and Instruction Manual. Use banana-to-grabber wires and alligator clips to make this connection. 6. To measure the gain of this amplifier, we need to turn off the AGC otherwise it will lower the gain as we try to measure it. Using another banana-to-grabber wire with another alligator clip, short TP3 to R38 as shown in Fig. 19 on page 22 of the Assembly and Instruction Manual. Be careful on how you position the alligator clip so that you don t short other points on the radio. Monitor the supply current as an indicator of problems. 7. Set the scope to AC coupling for both channels. Connect one channel to TP4 and the other to the base of Q8. 8. Turn ON the function generator output and set the frequency to 455 khz and 20 mv P-P (High Z). Increase the amplitude of the function generator until the voltage at TP4 is approximately 4 V P-P. 9. What we need to do next is make the amplifier resonate at 455 khz. We will do this again by varying the inductance of the coil. Using a small screwdriver, adjust T7 so that the gain from TP6 to TP4 is maximized. Re-adjust the function generator s amplitude to maintain an approximate 4 V P-P signal at TP4. Re-adjust T7 slightly to verify that the gain is maximum. Repeat if necessary. 10. Once T7 is aligned, measure the peak-to-peak voltage at TP4 (which is the collector of Q8) and at the base of Q8. Record and calculate the gain of the 1st IF Amplifier. It may be in the range of 100 to 300. 11. Print these waveforms for each member of your group. Mark which Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 8
waveform is which. Mark this section letter and number on the top right side of your plot and attach it as indicated in the Lab Report. 12. Vary the frequency of the function generator and measure the upper and lower 3dB frequencies, that is, where the voltage at TP4 drops to 0.707 of its center frequency value. Record. As a check, calculate f o as indicated in the Lab Report. It should be very close to 455 khz. If not, repeat the bandwidth measurements. Calculate the bandwidth and Q o as indicated in the Lab Report which may be around 6 khz and 65, respectively. 13. To see the effect of the AGC circuit working, observe the voltage at TP4 while you remove the short circuit between TP3 and R38. The voltage should be greatly reduced. Print these waveforms for each member of your group. Mark which waveform is which. Mark this section letter and number on the top right side of your plot and attach it as indicated in the Lab Report. 14. Turn OFF and disconnect the power supply. 15. Turn the Output of the function generator OFF and disconnect it from the radio. F) AM Mixer, AM Oscillator and AM Antenna 1. Find and remove the parts listed on page 23 of the Assembly and Instruction Manual. These are in your AM RADIO PARTS bag. Measure the primary and secondary resistance of the red dot AM Oscillator coil (L5). Record in the Lab Report and calculate the resistance ratio. This should be around 14. If your ratio is way off ask your instructor for another red dot transformer. Complete the assembly instructions on pages 23-25. 2. Reconnect the power supply and turn ON the power supply. Again monitor the current for problems. 3. Measure the DC voltage at TP7. This should be approximately 1.6 volts. Record the value in the Lab Report. If your measured voltage differs by more than 0.5 volts, turn off the power. Check that R31, R32, R33 and Q7 are installed correctly or ask your instructor for help. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 9
4. Connect one channel of the scope to the collector of Q7. You should see a sinewave. As you rotate the ganged capacitor, the frequency should change. If your circuit fails this test, check that the ganged capacitor, C28, C29, C30, C31, L4 and L5 are installed correctly or ask your instructor for help. 5. Print this waveform for each member of your group. Mark this section letter and number on the top right side of your plot and attach it as indicated in the Lab Report. 6. Measure the frequency and record. 7. Turn OFF the volume control. G) AM Alignment with Test Equipment 1. Connect the function generator to TP7 through a 0.001:F capacitor from your Parts Box as shown in Fig. 24 on page 28 of the Assembly and Instruction Manual. Use banana-to-grabber wires and alligator clips to make this connection. 2. To do the alignment, we need to turn off the AM oscillator. Using another banana-to-grabber wire with another alligator clip, short TP6 to the collector of Q7 as shown in Fig. 24 on page 28 of the Assembly and Instruction Manual. This will kill the AM oscillator. Be careful on how you position the alligator clip so that you don t short other points on the radio. Monitor the supply current as an indicator of problems. 3. Connect one channel of the scope to TP2. Use AC coupling and averaging. 4. Turn ON the volume control and function generator output. Set the function generator to 455 khz with an amplitude of 10 mv P-P (High Z). Set the modulation frequency to 400 Hz at 80%. 5. Slightly increase or decrease the amplitude of the function generator until a less than perfect sustainable sinewave appears at TP2. This may be about 1.0 V P-P on the scope. Don t overdrive TP2 by making very large increases to the initial amplitude setting of the function generator. This will reduce the sensitivity of your tuning. Tune T6 with your screwdriver for a peak and adjust the generator, if necessary, to maintain for the same V P-P at TP2. Do likewise for T7. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 10
Repeat these steps until the IF alignment no longer needs to be changed. We have now the IF amplifiers set to 455 khz. 6. Record the peak-to peak value of TP2 and the function generator setting at 455 khz in the Lab Report. 7. Carefully remove the short circuit from TP6 to the collector of Q7. 8. Set the function generator to 540 khz with an amplitude of 20 mv P-P (High Z). Leave the modulation frequency at 400 Hz and 80%. Remove the 10S load and adjust the volume to a comfortable level for you and the groups around you. 9. Turn the tuning knob counter-clockwise until the white pointer is aligned at the 540 khz marking on the dial. With your screwdriver adjust L5 until a 400 Hz tone is heard. Adjust L5 so that the gain from TP7 to TP2 is maximized. Adjust the amplitude of the function generator to maintain a level of 1.5 V P-P or less. 10. After peaking L5, set the function generator to 1.6 MHz. Turn the tuning knob clockwise until the white pointer is aligned to the 1600 khz marking on the dial. 11. Carefully rotate the radio so that you can view the back side of the pc board. Watch the power supply current for surges that might indicate a shorting of points. Refer to Fig. 25 on page 29 of the Assembly and Instruction Manual to locate the trimmer capacitors based on which gang capacitor was shipped as explained in Fig. L on page 24. Find your AM oscillator trimmer shown in Fig. 25 of page 29 of the Assembly and Instruction Manual. With the alignment tool we use to adjust the scope probes, adjust the AM oscillator trimmer on the back of the tuning gang until a 400 Hz tone is heard. 12. Adjust the trimmer so that the gain from TP7 to TP2 is maximized. 13. Repeat steps 8-12 until no further adjustment is needed. This process sets the oscillator range from 955 khz to 2.055 MHz which is the AM radio band plus 455 khz. 14. Turn OFF the volume control. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 11
H) Antenna Alignment 1. Using a banana wire create a closed loop antenna on the function generator s banana connectors as shown in Fig. 26 on page 29 of the Assembly and Instruction Manual. Monitor TP2 with the scope in AC coupling. 2. Turn ON the volume control. Set the function generator to 600 khz with an amplitude of 1V P-P (High Z). Set the modulation frequency to 400 Hz at 80%. Set the tuning knob fully counter-clockwise. Turn the knob clockwise until a 400 Hz sinewave appears on the scope. Adjust the volume control to a comfortable level for your and the groups around you. 3. If a radio station exists at 600 khz then lower the frequency of the generator and repeat step 2. 4. Remove the shim if you inserted it, as shown on the top of page 24 of the Assembly and Instruction Manual, to hold the antenna coil in place. Slide the antenna coil on the ferrite rod until signal is maximum or nearly maximum. Reinsert the shim to hold the antenna coil in place. 5. Set the function generator to 1.4 MHz. Turn the knob clockwise until a 400 Hz sinewave appears on the scope. If a radio station exists at 1400 khz then increase the frequency of the generator and repeat this step. 6. Decrease the amplitude of the function generator until the signal on the scope is about 400 mv P-P. Carefully rotate the radio so that you can view the back side of the pc board. Watch the power supply current for surges that might indicate a shorting of points. Refer to Fig. 25 on page 29 of the Assembly and Instruction Manual to locate the trimmer capacitors based on which gang capacitor was shipped as explained in Fig. L on page 24. Find your AM antenna trimmer shown in Fig. 25 of page 29 of the Assembly and Instruction Manual. Adjust the AM antenna trimmer for a peak on the scope. It should be very sensitive to small changes. If not reduce the input of the function generator and repeat this step. With the antenna properly aligned, carefully apply a small amount of glue (see lab instructor) to your antenna coil to prevent it from moving. After the glue dries you can remove the shim or just leave it there. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 12
Turn off and remove the function generator. You should be able to find several AM radio stations with your tuning knob. 7. Use the sub-miniature plug to connect the JBL speaker on your lab bench instead of the 2" speaker included with the AM radio. You will need to use a BNC-to-banana adaptor to do this. Notice the improvement in sound quality. 8. To truly see the mixing, tune your radio to a station. Record the approximate frequency by reading it off your tuning knob. Display on one channel of the scope the AM oscillator by placing the scope probe at the collector of Q 7 which is dominated by the AM oscillator. Place the other probe at the collector of the 2 nd IF amplifier which is TP3. Measure the frequency of each channel using the Toolbar. Calculate the difference. This should be the radio station s frequency. Record in the Lab Report. 9. Print these waveforms for each member of your group. Mark which waveform is which. Mark this section letter and number on the top right side of your plot and attach it as indicated in the Lab Report. 10. Demonstrate the operation of your AM radio to your lab instructor. Have the instructor sign off on this in the Lab Report. I) Clean up Please return all wires to the racks from which they were taken. Put the 9 volt adaptor back into the Parts Box. Turn off all equipment and brush off your bench. Put all of your radio parts back into the box, make sure your name is on the box. Place the box on one of the storage shelves. J) Lab Report 1. Finish your Lab Report at home. 2. Run the simulations found in the Lab Lecture notes to create your own input files. (Please note an error on p.23 where Vc should have been listed as 0.1 and not 1u). Don t re-type the semiconductors models but use the values in the library file on the ECE 404 home page. Compare your output to the lecture notes to make sure you have not made any typing mistakes. Please, to save paper, don t turn in this work. 3. Re-run these simulations and re-do the calculations found in the Lab Lecture notes to verify your lab data. Make a table for comparison between measured and simulated results. Note the following: Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 13
a. For the simulation on p.7, use the turns ratio you measured for T8 to re-calculate the value of L3 assuming that L12 is approximately the same as given on p.7. Your measured TP5 in VI-C-2 is V(34). Set Vc = (1/4) of V FG p-p measured in VI-C-2. Run the simulation and print the V(38), V(36) and V(34) like p.8 of the lecture notes as well as the input file. b. For the simulation on p.13,use the values of L1 and L2 given which are one-half of L12 above. Use a 0.02 uf for C37 in your simulations because that is the value used in your radio. Vary Rload for repeated simulations until you get the gain you measured at TP3 which is V(21) in VI-D-8. For that last simulation print V(21)/V(22) as well as the input file. Repeat the measurements of VI-D-10 but on your simulated results. Record. c. For the simulation on p.17, use the turns ratio you measured for T7 to re-calculate the value of L3 assuming L1 and L2 are approximately the same as given on p.17. Use a 0.02 uf for C35 in your simulations because that is the value used in your radio. Vary Rload22 for repeated simulations until you get the gain you measured at TP4 which is V(31) in VI-E-10. For that last simulation print V(31)/V(32) as well as the input file. Repeat the measurements of VI-E-12 but on your simulated results. Record. d. For the simulation on p.23, use the turns ratio you measured for T6 to re-calculate the value of L3 assuming L1 and L2 are approximately the same as given on p.23. Likewise, use the turns ratio you measured for T5 to re-calculate the value of L6 assuming L4 and L5 are approximately the same as given on p. 23. Set the value of fc in the simulation to the radio station you received in VI-H-8. Re-calculate the value of CT1 to give the frequency f ot5 = 455 k + your radio station frequency. Plot and measure the frequency of V(46,47) and V(32). Plot the spectrum of V(41) and V(32). Print your input file. 4. Use the information that you have gathered to write a qualitative description of how the AM radio works. Try to incorporate your lab data in the description. This due at the next lab meeting after completion of step VI-H-10. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 14
Lab Report Lab III - AM/FM Radio - AM Radio Name:... Partner:... Date:... Lab Section Number... Lab Station Number... Code of Ethics Declaration All of the attached work was performed by our lab group as listed above. We did not obtain any information or data from any other group in this lab or any other lab section. Signature... Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 15
VI-A-3 Primary resistance (black dot) = R P = Secondary resistance (black dot) = R S = Approximate Turns Ratio (black dot) = R P / R S = Primary resistance (yellow dot) = R P = Secondary resistance (yellow dot) = R S = Approximate Turns Ratio (yellow dot) = R P / R S = VI-B-7 V TP5 = VI-C-2 V FG = V TP5 = VI-C-8 Mark VI-C-8 on the top right side of your plot and attach as the next page. VI-C-9 Bandwidth = VI-C-10 Mark VI-C-10 on the top right side of your plot and attach behind VI-C-8. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 16
VI-D-1 Primary resistance (white dot) = R P = Secondary resistance (white dot) = R S = Approximate Turns Ratio (white dot) = R P / R S = VI-D-3 V EQ9 = VI-D-8 V TP3 = V p-p V BQ9 = V p-p Gain = VI-D-9 Mark VI-D-9 on the top right side of your plot and attach as the next page. VI-D-10 Upper -3dB frequency ( f UPPER ) = Lower -3dB frequency ( f LOWER )= f o = [ f UPPER C f LOWER ] 0.5 = BW = f UPPER - f LOWER = Q o = f o /( f UPPER - f LOWER ) = Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 17
VI-E-3 V TP5 = VI-E-4 V EQ8 = VI-E-10 V TP4 = V p-p V BQ8 = V p-p Gain = VI-E-11 Mark VI-E-11 on the top right side of your plot and attach as the next page. VI-E-12 Upper -3dB frequency ( f UPPER ) = Lower -3dB frequency ( f LOWER )= f o = [ f UPPER C f LOWER ] 0.5 = BW = f UPPER - f LOWER = Q o = f o /( f UPPER - f LOWER ) = VI-E-13 Mark VI-E-13 on the top right side of your plot and attach behind VI-E- 11. Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 18
VI-F-1 Primary resistance (red dot) = R P = Secondary resistance (red dot) = R S = Approximate Turns Ratio (red dot) = R P / R S = VI-F-3 V TP7 = VI-F-5 Mark VI-F-5 on the top right side of your plot and attach as the next page. VI-F-6 f OSC = VI-G-6 V TP2 = V FG = V p-p V p-p VI-H-8 Approximate radio station reading off knob = Frequency of V C Q7 = f 1 = Frequency of V TP3 = f 2 = f 1 - f 2 = VI-H-9 Mark VI-H-9 on the top right side of your plot and attach behind VI-F-5. VI-H-10 I observed the proper operation of the AM radio Copyright 2008 by Gregory M. Wierzba. All rights reserved...fall 2008. 19