SG80 AM STEREO - FM STEREO ANALYZER Operation and Application Manual S=NCOR= Ge 9068 ©f O20 T == (C-QUAM is a registered Trademark of Motorola, Inc.) SENCOR ‘3200 Sencore Drive, Sioux Falls, South Dakota 57107WARNING PLEASE OBSERVE THESE SAFETY PRECAUTIONS There is always a danger present when testing electronic equipment. Unexpected high voltages can be present at unusual locations in defective equipment. Every precaution has been taken in the design of your instrument to insure that it is as safe as possible. However, safe operation depends on you, the operator. Become familiar with the equip- ‘ment you're working with, and observe the following safety precautions: 1, Never exceed the limits of this instrument as given in the specifications section and the additional special warnings in this manual. 2. A severe shock hazard can result if the chassis of the equipment being serviced is tied to the “hot” side of the AC line, An isolation transformer should always be used with hot-chassis equipment. Also, be sure that the top of your workbench and the floor underneath it are dry and made of non-conductive materials. 3, Remove the circuit power before making connections to high voltage points. If this cannot be done, be sure to avoid contact with other equipment or metal objects. Place one hand in your pocket and stand on an insulated floor to reduce the possibility of shock. 4, Discharge filter capacitors (after removing power) before connecting to any part of the cirenit requiring power to be removed. 5. Be sure your equipment is in good order. Broken or frayed test leads can be extremely dangerous and can expose you to dangerous voltages. 6. Remove the test lead immediately after the test has been completed to reduce the possibility of shock. 7. Do not work alone when working on hazardous cireuits. Always have another person close by in case of an accident. Remember, even a minor shock can be the cause of'a more serious accident, such as falling against the equipment, or coming in contact with high voltages.SG80 AM STEREO - FM STEREO ANALYZER Operation and Application Manual (C-QUAM is a registered Trademark of Motorola, Inc.) SENCORE 9200 Sencore Drive, Sioux Falls, South Dakota S707 1TABLE OF CONTENTS SAFETY PRECAUTIONS, Inside Front Cover DESCRIPTION Introduetion Features.. Specifications Controls Rear Panel Features ‘Supplied Accessories Optional Accessories OPERATION Introduetion Power Connections AC Line Protection Fuse. RF-IF Signal Connections .. ‘50 Ohm Impedance Connections. 75 Ohm Impedance Connections. 300 Ohm Impedance Connection Selecting the RFP Outpt Rang RFF Toning... Using The RF-IF MPX Signals... SCA 67 kilz : 75 uS Pre-Emphasi Using The Audio Drive . Using The External Modulation Input. AUTOMATED BUS OPERATION Introduction. ssn . Connecting the SG80 To The Interface Bus .. Using the SG80 As A Listener .. ‘Command Descriptions... Error Codes . Using The SG8 APPLICATIONS Index .. os Performance Testing ‘Of FM Tuners! Receivers .. eve 25-35 Performance Testing AM Mono And Stereo Tuner) Receivers... 36-44 FM Stereo Receiver Troubleshooting And Alignment, 45-55 AM Stereo Receiver Troubl eshooting ‘And Alignment... APPENDIX A FM Trouble Tree and Block Diagram... 63 AM Trouble Tree and Block Diagram nnn 50, 75, 300 Ohm RF Level Chart... sen What is a dB? .. “ Voltage to dB Conversion Chart .. APPENDIX B FM Stereo Theory ..... AM Stereo (C-QUAM) Theory .. GLOSSARY. SERVICE AND WARRANTY... Inside Back CoverDESCRIPTION Introduction ‘The SG80 is a patented stand alone stereo receiver analyzer that provides known good signals for testing today's complex audio circuitry. By injecting the SG80's signals into the stereo under test, performance tests, alignments and troubleshooting can be done with com: plete confidence. Features ‘Many features cambine to make the SG80 a total stereo receiver analyzer: ‘The SG80RF-IF generator has the tuning range and accuracy needed to service tuners and receivers. ‘The SG80 provides precision RF and IF signals for testingand aligning FM tuners andreceivers. RF and IF tuning is selectable as follows: RF/IF Signal Coarse Tuning Steps Fine Tuning Steps FMRF 200 ke 30H AMRF 10 kHz 1 kHz, FMF 100 kit 10 kHz AM IF 10% kHz swe 100 kHz 10% Modulation distortion of less than 0.01% for FM and 0.5% for AM allows you to test the most modern high- fidelity receivers as well as older stereo receivers. ‘The FMSWP function equipsyouforsweep alignment, of FM receivers. The SG80 provides external vertical and horizontal sweep for the scope using the TO SCOPE VERT and HORIZ connectors. Plus, a tuneable center marker (9.7 to 1.7 MHz) with markers at 100 kHz intervals from center ‘ets you check amplifiers and filters quickly and accurately. Analyze AM mono and C-QUAM ® AM Stereo. The RF-IF generator allows testing and aligning of AM re- ceivers. You can tune RF frequencies from 520 kHz to 1720 kHz with 1 kHz tuning steps. IF frequencies from 200 kHz to500kHz with 1kilz steps allows youto do AM. IF alignments.SCA Capability: The SG80 generates a modulated 67 ‘kHlz signal for setting Subsidiary Communication Au- thority (SCA) filters and testing the operation of SCA tuners and receivers, Anadjustable pilot level from 0% to 120% allows you to test and adjust the pilot threshold of AM and FM Stereo tuners and receivers. Adjustable audio output signals let you test the am- plifier section of receivers. An audio level control is pro- vided to adjust the output of the audio generator from 0 VPP to 3 VPP, with 0 or 180 degree phase inversion, Specifications All specifications allow for 20 minutes of warmup and are guaranteed at 15-45 degrees C (59-118 degrees F). FM RF GENERATOR ‘Tuning Range 87.9 to 108 MHz ‘Tuning steps Coarse 200 kHz steps Fine 10 kHz steps Accuracy +/-20 PPM Modulation Percentage 100% = +/- 75 kHz De- viation +/- 2 kHz << or equal to 0.01% THD with a 1 kHz sinewave @ 100% mod. > 63 4B @ 98.1 MHz and 1 kfiz sinewave modulation ‘Modulation Distortion ‘Stereo Separation FM IF GENERATOR (Specs guaranteed from 10.2 ‘Mz to 11.2 MHz) ‘Tuning Range 9.7 to 11.7 MHz, ‘Toning Steps Coarse 100 kHz Fine 10 kHz Accuracy +/-20 PPM Modulation Percentage ‘100% = +/- 75 kHz deviation +/- 2 kHz < or equal to 0.01% ‘THD with a 1 kHz sinewave @ 100% mod. Modulation Distortion FM MULTIPLEX GENERATOR Pilot Frequency 19 kHz +/-2 Ha Pilot Level 0 to 10% of overall 11% + 1% modulation continavusly variable Stereo Separation ‘Through Composite > 65 db at 1 kHz SCA Frequency * 59 t0 95 KH internally adjustable. Preset at factory to 67 kHz Accuracy of Carrier +/-1.5 KHz Modulation 2.5 kHz audio sine ‘Modulation Distortion < or equal to 3% at 2.5, kHz INTERNAL FM MODULATION Modulation Frequency Off, 400 Hz, 1 kHz,and5 kHz +20 PPM Sine and Squarewave EXTERNAL FM MODULATION Freq. Range 30 Hz to 15 kHz (flat to within +/-1.5 dB) 600 ohms 4/- 15% 3 VPP audio sinewave signal at 1 kHz with- out pre-emphasis +/- Input Impedance Level for 100% Mod. 0% Pre-emphasis 75 usec front pane selectable FM SWEEP GENERATOR. ‘Sweep Width -+/- 600 Hz, Center Marker Frequency Selectable between 9.7 and 11.7 MHz in 100 kHz steps (Coarse) and 10 kz steps (Fine) Accuracy +/-20 PPM Amplitude 1.2 VPP Minium Markers Every 100 kHz from center marker to “+ 600 kz AMRF GENERATOR Frequency Range 520 kHz to 1720 kHz minimum ‘Tuning steps Coarse 10 kHz steps Fine 1 kHz steps Accuracy of Carrier +/-20 PPM Modulation Percentage fe to 125% +/- 29% in Mono, L+R, L-R, and Stereo 0% to 65% in R and L or equal to 35 dB from 200 Hz to 7.5 kHz at 50% modulation 25 He +/- 0.25 Ha ‘Sub-Channel Mod. Dist, Stereo Separation ID Pilot Frequency RE/IF/MPX ATTENUATOR Range 0 to 120 dBf Continu- ously Variable (0.27 uV to 0.270) 41-1 dB at 98.1 MHz at 65 dBf +/- 1.5 dB over 20 dBf-120 dBF ‘anges, +/-2.5 dB over OdB range 75 Ohm RF, 1k Ohm ‘MPX Protected from exter- nally applied voltages up to +/- 400 VDC + Peak AC) Accuracy Output Impedance Output Protection AUDIOOUTPUT Frequencies Off, 400 Hz, 1kHa, and 5 kHz +20 PPM Sinewave and Square wave < 0.02% THD at 1 kHz into 100 ohms Sinewave Distortion Output Amplitude 0 to3 VPP continu- ously variable into 100 ohms Output Impedance 100 ohms Output Protection Protected from exter- nally applied voltages +/- 500 volts (DC + Peak AC) Floating Ground () ground isolated to +/-500V (DC + Peak AO) GENERAL SPECIFICATIONS Operating Temperature 15 to 45 degrees C Humidity -< 90% RH with no con- densation AC Power 105 to 180 VAC, 60 Hz, 35 watts Size 7 V4" x 13 3/4" x 15" HWD (18.4 emx 34.9 em x 38.1 em) Weight 20 pounds (10.8 kg) Warmn-sp Time 20 minutes Recommended Recalibration interval is one year. All specifications subject to change without notice. ‘SUPPLIED ACCESSORIES: 39G227 AUTO RADIO ANTENNA TEST LEAD 39G72 75-300 MATCHING TRANS. 39G220 BNC-TO-F CABLE. ~ 39G221 TEST LEAD \.39G222 FM DETECTOR PROBE 39G223 VERT BNC-TO-BNC CABLE 39G224 HORIZ BNC-T0-BNC CABLE ~+39G226 AM MATCHING PAD OPTIONAL ACCESSORIES: PC259 Protective Cover/Lead storage 1B72 IEEE 488 Bus Interface Accessory 1B78 RS232 Interface AccessoryControls 1. RF-IF MPX SIGNAL. Selects four FM and two AM output signals to performance test, troubleshoot, and align receivers. 1a, FMRF- Providesan FM RF signal tunable from 87.9 MHz to 108 MHfz with frequeney modulation adjustable from 0 to 125%. Modulation is controlled by the AM & FMMPX MODE (12), AUDIO (11), and AUDIO MODU- LATION (10) controls. The FM RF signal is available at the RF-IF MPX OUTPUT connector (19). 1b, FM IF- Provides an FM IF signal tunable from 9.7 Miz to 11.7 MHz with frequency modulation adjustable from 0 to 125%. Modulation is controlled by the AM & FMMPX MODE (12), AUDIO (11), and AUDIO MODU- LATION (10) controls. The FM IF signal is available at the RF-IF MPX OUTPUT connector (19). 1c. FM MPX- Provides the MPX signal selected by the AM & FM MPX MODE switch (12). The FM MPX signal is available at the RF-IF MPX OUTPUT connector (19). ‘The MPX output level is adjusted by the RF-IF MPX VERNIER (3). 8 dany are etn nL 1d. FM SWP. Provides a sweep signal with a center frequency tunable from 9.7 MHz to 11.7 MHz with the RE-IF TUNING control (7), and a fixed sweep width of ++/-600 kHz. A center marker and 100 kHz side markers are generated and added tothesweep response at the TO SCOPE VERT output jack (17¢). Je. AMRF- Providesan AM RF signal tunable from 520 kHz to 1720 kHz with amplitude modulation adjustable from to 1009 (0 to 65% R only and Lonly). Modulation is controlled by the AM & FM MPX MODE (12), AUDIO (11), and AUDIO MODULATION (10) controls. The AM RF signal is available at the RF-IF MPX OUTPUT con- nector (19). 1£, AM IF- Provides an AM IF signal tunable from/S00 KHz to 500 kHz with amplitude modulation adjustable from 0 to 100% (0 to 65% R only and Lonly). Modulation is controlled by the AM & FM MPX MODE (12), AUDIO (41), and AUDIO MODULATION (10) controls. The AM IF signal ig available at the RF-IF MPX OUTPUT connector (19).2. RF-IF RANGE switch - Sets the RF-IF output in 20 ABE steps from 0 to 100 BF (Has no effect in MPX). 2a, 0 dBf, X 1- In this position, the output level is adjusted by the RF-IF MPX VERNIER (3) from 0 dBf to 20 ABf (.27 to 2.7 microvolts). 2b, 20 ABE, X 10- In this position, the output level is ‘adjusted by the RF-IF MPX VERNIER (3) from 20 dBf to 40 dBf (2.7 to 27 microvolts). 2c, 40 ABE, X 100- In this position, the output level is adjusted by the RF-IF MPX VERNIER (8) from 40dBfto 60 dBF (27 to 270 microvolts). 24, 60 ABE, X 1 K- In this position, the output level is adjusted by the RF-IF MPX VERNIER (3) from 60 dBf to 80 BE (270 to 2,700 microvolts). 2e, 80 dBf, X 10 K- In this position, the output level is adjusted by the RF-IF MPX VERNIER (8) from 80 dBfto 100 ABE (2,700 to 27,000 microvolts). 2f. 100 dBf, X 100 K- In this position, the output level is adjusted by the RF-IF MPX VERNIER (3) from 100 ABE to 120 ABE (27,000 to 270,000 microvolts). 3, RF-IF MPX VERNIER - Varies the level of the RF- IF output from 0 to 20 dB. This output is in addition to the level selected by the RF-IF RANGE switch (2). 4. SCA switch - Selects the 67 kHz SCA signal for aligning and testing FM receivers. 5. EXTENDED RANGE FM switch - Selects the Bx- tended Range FM signal, for testing extended range FM receivers. 6, FREQUENCY display - 4 1/2 digit LCD with kHz and MHz annuneiators. Displays the frequency of the BF, IF, and MPX output signals, 7. RE-IF TUNING control - Controls the RF-IF gen- erator frequency in both coarse and fine steps. Switches between coarse and fine when control is pushed. ‘Ja. DOWN direction - Turnirig the RF-IF TUNING control (7) counter-clockwise decreases the RF-IF gen- erator frequency. Wrap around feature speeds servicing by allowing tuning through from lowest ta highest fre- quency. ‘Tb. UP direction - Turning the RF-IF TUNING control (1) clockwise increases the RF-IF generator frequency. Wrap around feature speeds servicing by allowing tun- ing through from highest to lowest frequency. ‘7e. PUSH TO CHANGE TUNING SPEED - When pushed, the RF-IF TUNING control (7) changes between, 200 kitiz. and 10 kHz steps for FM RF signals, 100 kHz and 10kHzsteps for FM IF and SWP signals, and 10kHz ‘and 1 kHz steps for AM RF and IF signals. 8 PILOT MODULATION control - Adjusts the pilot level from 0% to 125% of normal pilot level for both AM and FM Stereo. Disabled when the AM & FM MPX, ‘MODE switch (12)is in the MONAURAL (12a) position, 8a, PILOT OFF NORMAL WHEN LIT indicator - When lit, alerts you that the pilot is adjusted to a level other than the normal modulation level. 9. MODULATION display - Displays the level of total ‘modulation in FM including pilot in the FM Stereo mode and audiomadulation in AM mode as adjusted by AUDIO MODULATION eontrs! (10). 10, AUDIO MODULATION control - Adjusts audio modulation level from 0 to 100% for AM (0 to 65% in R only and Lonly),and 0to 125% for FM. Level is displayed on the MODULATION display (9). 11. AUDIO switch- Provides no modulation, sine or squarewave modulation signals at 400 Hz, 1 kHz, or 5 kHz, or modulation with external audio. ‘Via. OFF- Tums off audio modulation. 1b. 400 Hz sine wave- Provides 400 Hz sine wave ‘modulation on the RF-IF MPX OUTPUT and 400 Hz sine wave audio at the AUDIO DRIVE output. Le, 1 kHz sine wave Provides 1 kHz sine wave modu- lation on the RF-IF MPX OUTPUT and 1 kHz sine wave audio at the AUDIO DRIVE output. Lid. 5 kHz sine wave - Pfovides 5 kHz sine wave ‘modulation on the RF-IF MPX OUTPUT and 5 kFiz sine wave audio at the AUDIO DRIVE output. Le, 400 Hz square wave -Provides 400 Hz square ‘wave modulation on the RF-IF MPX OUTPUT and 400 ‘Hz square wave audio at the AUDIO DRIVE autput, 11f. 1 kHz square wave- Provides 1 kHz square wave modulation on the RF-IF MPX OUTPUT and 1 kHz square wave audio at the AUDIO DRIVE output, Lig. 5 kiiz square wave- Provides 5 kHz square wave modulation on the RF-IF MPX OUTPUT and 5 kHz square wave audio at the AUDIO DRIVE output, 11h, EXT- Provides external modulation on the RELI MPX OUTPUT with the audio signals connected to the EXT AUDIO input jacks (14). There is no signal at the AUDIO DRIVE output when usingexternal modulation. 12, AM & FM MPX MODE switch - Controls the type of MPX signal produced by the SG80. This signal modu- lates the RF-IF MPX OUTPUT or is available directly atthe RF-IF MPX OUTPUT (FM only), when the RF-IF SIGNAL switch is in the MPX position (10). The type of audio signal is controlled by the AUDIO switch (11). 12a. MONAURAL - Provides a monaural signal at the frequency selected by the AUDIO switch (11). No pilot is produced with this signal. 12b, STEREO - Provides a stereo signal with the right. channel equal to (in phase with) the left channel when using internal signals. You can inject different signals using the EXT inputs. The pilot level is adjustable with the PILOT MODULATION control (8). 12¢. LR - Provides L+R and pilot MPX signals. The pilot level is adjustable with the PILOT MODULATION control (8). 12d.L-R -Provides L-Rand pilot MPX signals. The pilot level is adjustable with the PILOT MODULATION control (8). 12e, R ONLY- Provides right channel modulation only. ‘The pilot level is adjustable with the PILOT MODULA- TION control (8). 12f. L ONLY - Provides left channel modulation only. ‘The pilot level is adjustable with the PILOT MODULA. TTION control (8). 13, 75 uS PRE-EMPHASIS switch - Provides 75 microsecond pre-emphasis when the switch isin, When the switch is out, there is no pre-emphasis of the audio signals. 14. EXT AUDIO INjacks- Input connectors forleft and right external audio signals for use in the EXT position of the AUDIO switch (11h). 15. AUDIODRIVEcontrol- Adjusts the AUDIODRIVE, ‘output level from 0 to +/-3 VPP. Phase is 180 degrees on the left half of center detent and 0 degrees on the right, CW, half of the detent, 16, AUDIO DRIVE connector (has floating ground» Supplies audio signal selected by the AUDIO switch an. 17. FM-IF SWEEP & MARKER SIGNALS. Use this section to test and align FM IF circuits. 17a. MARKER HEIGHT control - Adjusts the ampli- tude of the IF markers at the scope vertical marker output. 1 7b. TO SCOPE HORIZ connector -Provides sweep signal to an oscilloscope’s horizontal input (Ch. B when using the scope’s veetor mode) for use with the FM SWP. (2d) fanetion. fe. TO SCOPE VERT connector -Providessignaltoan oscilloscope’s vertical input (Ch. A) for use with the FM SWP (14) function, This output signal is the same as the signal applied to the FROM FM DETECTOR connector (174) with the center and 100 kHiz side markers added. 17d. FROM FM DETECTOR connector - Provides input from the receiver under test when the FM SWP function is in use. 18. PULL CHART - Provides simplified operating in- struetions for quick reference. 19. RF-IF MPX OUTPUT connector - Provides an output for all RF, IF, and MPX signals. 20. POWER switch - Applies power to the unit. Switch is illuminated when on. Rear Panel Features 21, INTERFACE ACCESSORY JACK- This jack con- neets either the IEEE 488 Bus Accessory or the RS232 accessory to the SG80. 22, AC LINE fuse- This fuse protects the SG80 from damage should a failure occur causing the unit to draw excessive current, Replace the fuse with the correct type and rating. (1 Amp, 3G, 250V, Slo-Blo) 23, ACLINE CORD- Connect the AC line cord to a 105- 130 VAC, 60 Hz, 35 W source only when operating the S80. Supplied Accessories 24, 39G227 ANTENNA TEST LEAD - Use when con- necting the SG80 to the antenna input of ear radios. 25. 39G72 75-800 MATCHING TRANSFORMER - ‘The 39G72 transformer is used to convert from the standard 75ohm output of the SG80 to300 ohm antenna terminals. (Output level correction must be used when changing load impedances.) 26, 396220 BNC-TO-F CABLE- This cable is for use when connecting the SG80 to the component under test. Connect the BNC end to the RF-IF MPX OUTPUT (19) connector, and the F connector end to the tuner or receiver. 27,39G221 TEST LEAD. Use the 39G221 TESTLEAD for injecting audio from the AUDIO DRIVE (16) connec- tor on the SG80.28, 396222 FM DETECTOR PROBE- The detector probe is used when aligning and troubleshooting FM IF citeuits. The probe uses three leads for connecting to the IF circuits; black is the ground, red is an isolated direct connection, and blue is the detector lead. 29, 39G223 VERT BNC-TO-BNC CABLE: This cable is to be connected to the left. EXT AUDIO input on the ‘SG80, when supplying an external audio source. 30, 89G224 HORZ BNC-TO-BNC CABLE- Connect this cable to the right EXT AUDIO input of the SG80, when supplying an external audio source. 31, 39G226 AM MATCHING PAD -75 ohm to 50 ohm; voltage out equals voltage in divided by 10. Use the 390226 with the SG80 when connectingan AM signal to atuner/receiver, which supplies AM antenna terminals, Optional Accessories 32, IB72 IEEE 488 1: BUS INTERFACE ACCES- SORY- Connects between the INTERFACE ACCES. SORY JACK (21) and IEEE 488 port of a bus controller ‘toallow the SG80 tobe used on an IEEE 488bus system. 38, PC259 PROTECTIVE COVER/LEAD STORAGE- Snap on cover ta protect the front panel of the SG80 and to provide a storage space for the leads during transpor- tation, 94, IB78 RS232 INTERFACE ACCESSORY- Con- nects between the INTERFACE ACCESSORY JACK (21) and the serial RS232 port of a controller to allow the SG80 to be used for automated testing. Fig. 2. Rear Panel Features of the SG80 ¥i) Q {Fig. 3: Supplied Accessories Fig. 4: Optional AccessoriesA review of both AM C-QUAM and FM Stereo theory is given in Appendix B on page 47. Review the Appendix section prior to using the SG80. OPERATION Introduction This section will help you understand the operation of the SG80, For details on how to test tuners or receivers, refer to the APPLICATION section of this manual. Before-using your G80 AM STEREO- FM STEREO ANALYZER for thefirst time, takea few minutestoread the OPERATION and APPLICATION sections of this manual. The PULLCHART, located under the unit, pro- vides quick reference information for day to day opera- tion. Power Connections ‘The SG80 is powered by a standard 105-130V AC line. ‘The power cord, connected to the rear of the unit, uses a Figure §: Connect the SG80's AC line cordtoaproperly grounded 105-130 VAC 60 Hz source, and press the POWER button to the on position. i 3rd wire ground pin, Do not defeat the Srd wire ground, it provides for proper shielding, operation, and safety. Always verify thatthe AC soureehasa properly grounded outlet. To operate the SG80 from an AC line: 1. Conneét the AG cord on the rear of the SG80 to a properly grounded AC source (105-130V, 50-60 Hz). 2, Press the POWER switch on the front of the SG80 to the on position. A lightin the power switch will come on, confirming that the unit is receiving power. Figure 6: The AC line fuse is located next to the line. cord, and is easily removed. 3. The SG80 is ready for use immediately after applying power. If precise measurements are required, allow the unit to operate for 20 minutes to reach the specified ac- curacy.WARNING ‘TheSG80 must be operated by aproperly grounded 3rd wire outlet supplying 105-130V AC at 50-60 Hz for safe operation and minima} interference. De- feating the ground pin on the SG80 voids all war- ranties, AC Line Protection Fuse ‘The SG80usesa 1 Amp, 3AG, 250V, Slo-Blo type AC line fuse. If the fuse should open, find the cause prior to replacing the fuse. Replace the fuse only with thecorrect type and rating. Incorrect fuses void all warranties. WARNING Improper fuses void all warranties. Always re- place the AC line fuse with the proper type and rating (1 Amp, 3AG, Slo-Blo). To replace the AC line fuse: 1. Press to release the snap in fuse holder. 2. Carefully withdraw the holder and fuse. 3, Replace the fuse with a new one of the correct type and rating, 4, Reinsert the fuse holder and press to snap in place. @ [AM STEREO C-OUAM" FORMAT Lenses an tees Figure 7: Connect the poper leads and accessories to ‘match the signal being used. 19 RF-IF Signal Connections Many modern tuners and receivers permit a 80, 75, or 300 ohm antenna to be connected, The SG80 can be used to supply asignal for any ofthese inputimpedances. Use the following procedures when connecting to the RF terminals. 50 Ohm Impedance Connections - Use the 396226 AM Matching Pad and divide the microvolt RF-IF MPX microvolt level by 10. (-20 dBfis approximately equal to Bf out). ‘The $G80 can be connected to50 ohm antenna inputs as used by most AM antennas using the39G226 AM Match- ing Pad. The output level of the SG80 must be compen- sated to match the change in output impedance from 75 ohms, Simply divide the front panel microvolt readings by 10 (or subtract 20 dB®, to obtain the correct level readings ‘To connect the SG80 to a 50 chm terminal: 1. Conneet the supplied 39G226's BNC connector to the RF-IF MPX OUTPUT jack. 2. Connect the alligator clips on the other end of the 39G226 cable to the AM radio's antenna terminals (GND to GND, signal input to antenaa input.) 3. Divide the microvolt output levels on the front panel of the SG80 by 10 (or subtract 20 dB). 75 Ohm Impedance Coznections: ‘The SG80 supplies an RF signal calibrated for a 75 ohm input using the supplied 39G220 cable, When connect- ing to a 75 ohm input, the calibration of the SG80 RF ‘output level is as marked on the front panel. To connect the SG80 to 4 75 ohm RF terminal: 1, Connect the supplied 296220 cable’s BNC end to the ‘SG80's RF-IF MPX OUTPUT. 2, Connectthe F connector end of the 39G220 eableto the tuner or receiver antenna input. 3. The output levels marked on the RF-IF MPX QUT- PUT LEVEL switches are calibrated for the 73’ ohm impedance. Read the level directly from the SG80. 300 Ohm Impedance Connections - Use the 39672 MATCHING TRANS and multiply the RF-IF MPX microvolt level by 2. dBfequals the front panel reading.‘The SG80 may also be used to connect to antenna terminals having a 300 ohm impedance. When using a 300 ohm impedance, itis necessary to use the supplied 39G72MATCHING TRANS. The matching transformer converts the SG80's unbalanced 75 ohm output to a 300 ‘ohmbalanced output.'Themicrovolt output levels marked on the SG80's front panel must be modified to supply proper signal levels; however, power levels are correct. ‘Simply, multiply the microvolt levels marked on the front panel by 2 ‘To connect the SG80 to a 300 ohm antenna terminal: 1. Connect the supplied 39G220's BNC connector to the RF-IF MPX OUTPUT jack. 2. Connect the other end of the 39G220 cable to the supplied 39G72 MATCHING TRANS. 3, Connect the balanced output of the matching trans- former to the 300 ohm antenna terminal of the tuner or receiver under test. Selecting The RF-IF Output Range ‘The $G80 provides signal levels rom 0.27uV to 0.27V (0 to 120 dBQ), for simulating fringe and overload signal conditions. The RF-IF RANGE and RF-IF MPX VER- ‘NIER are used toset the output level, The RF-IF RANGE control is used as a multiplier for the RF-IF VERNIER, control. When testing a tuner or receiver, set the level to that specified in the service literature - or follow the procedure in the APPLICATION section of this manual. NOTE: Remember to compensate for the terminating impedance of the antenna terminals. When connected to a7 ohm load, the markings on the front panel are read directly. Ifconnected toa 300 ohm antenna terminal, you RF-IF OUTPUT LEVEL REAP RANGE, [RAF MPX VERNIER oe ey suv ssuv 2 oe ca van POWER AFAR MPX OUTPUT F Figure 6: Match the SG80's output level to the circuit under test. 13 ‘must multiply the microvolt level by 2 (read dBf directly). If using the 390226 AM MATCHING PAD, divide the microvolt settings by 10 (or subtract 20 dB). To set the RF-IF output level: 1. Set the coarse RF-IF RANGE control to the closest range below the level you wish to achieve (in the MPX position, the control has no effect). 2. Adjust the RF-IFMPX VERNIER control sothat when, itis added to the level set in step 1, the result is equal to the desired output level. RF-IF Tuning ‘The SG80 provides a digitally tuned RF or IF signal in both AM and FM modes, This permits easier and more accurate servicing of modern digital tuners/receivers. ‘Turning the RF-IF TUNING control clockwise increases the tuned frequency, while turning the control cocnter- clockwise decreases the tuned frequency. The wrap around feature lets you continue through the bend limits to the upper (or lower) frequencies. The SG80 permits tuning in either of two speeds. Pressing the RF- IF TUNING control changes the tuning from the normal tuning to the fine tuning speed. Pressing the control again returns the tuning to the normal tuning speed. FREQUENCY cr i NER REAP TUNING PILOT MODULA t om Vey Figure 9: The SG80 provides digital tuning for the FM AF, FM IF, AM RF, and AM IF formats. / Fine Tuning Standard Tuning FMRF 10 kHz steps 200 kHz steps FMIF 10 kHz steps 100 kHz steps ‘SwP 10 kz steps 100 kHz steps AMRF 1 kHz steps 10 kHz steps AMIF 1 kHz steps 10 kHz stepsUsing The RF-IF MPX Signals FMRF ‘The FM RF ostput is used to inject a signal with monaural or composite stereo modulation, as selected by the AM & FM MPX MODE switch, into the antenna input of FM receivers. The tuning range of the FM RF is from 87.9 MHz to 108 MHz. The signal is tuneable in either 200 kHiz or 10 kHz steps. To set the FM RF signal for a standard RF output: NOTE: The standard RF output level, according to THF standards, is 65 dBf with 1 kHz modulation, 1. Set the SG80 RF-IF MPX SIGNAL switch to the FM RF position. 2. Connect the 75 ohm cable to the RF-IF MPX OUTPUT jack and to the receiver under test. The cable should be properly terminated for connection to the SG80. 3, Set the AM & FMMPX MODE switch to the monaural or stereo position. 4. If stereo operation is selected, adjust the PILOT MODULATION to 100%, The red light at the lower left of the PILOT MODULATION control will turn off when. the control is at the 100% level. 5, Set the AUDIO switch to 1 kHz, 6, Turn the AUDIO MODULATION CONTROL up until the MODULATION display reads 100%, 7. Adjust the RF-IF TUNING control to the desired output frequency. The frequency is displayed in the FREQUENCY LCD readout in MHz for FM signals, RF-IF MPX SIGNAL MPX —SWP RE Figure 40: Use the FM RF, IF, MPX, And SWP signal for testing and troubleshooting an FM tuners and recelv- ers. Each click of the RF-IF TUNING control changes the frequency by 200'kHe (the unit may power up in Fine or Course tuning steps). To change tuning steps, press the control knob once. ‘To return, press the control knob a second time. 8, Set the RF-IF RANGE control to the 60 dBf range. Set the RF-IF MPX VERNIER control to the 5 dBf setting. ‘This gives a standard 65 dBf output level into 75 ohms. FMIF ‘The FM IF output is used to inject a signal with monau- ral or composite stereo modulation, as selected by the ‘AM & FM MPX MODE switch, into the IF amplifiers of FM receivers. This signal is used for IF testing and troubleshooting, The output frequency is variable using the RF-IF TUNING control and has a range from 9.7 ‘MHz to 11.7 Mz. To use the FM IF signal: 1, Set the SG80 RF-IF MPX SIGNAL switch to the FM IF position. 2. Connect the 75 ohm cable (39G220) to the RF-IFMPX OUTPUT jack. Connectthe 39G72 MATCHING TRANS to the other end of the 396220 cable. 3, Set the AM & FM MPX MODE switch to the desired position. 4, If a stereo receiver is being tested, turn the PILOT MODULATION control to 100%. When set at 100%, the red light below the PILOT MODULATION control will turn off. 5, Set the AUDIO switch to 1 kHz and the AUDIO MODULATION to 100%. 6, Adjust the RF-IF TUNING control to 10.7 MHz. The frequencyis displayed in the FREQUENCY LCD readout in MHz, Bach click ofthe RF-IF TUNING control changes the frequency (the unit may power up in Fine or Course ‘tuning steps. To change tuning steps, press the control knob once. To return, press the control knob a second time. 7, Adjust the RF-IF MPX OUTPUT LEVEL controls for 65 dB, member tocompensate or the terminatingim/ 1. 50 ohm 396226 AM MATCHING PAD — divide by 10 2. 75 ohm load — read directly 3. 300 ohm impedance — use the matching trans former andmultiply the microvolt reading by 2. Read dBf directly.MPX ‘The MPX signal from the SG80 providesa composite FM baseband audio signal for injection into the stereo multi- plex cireuits of the FM receiver. This signal can be used to align and/or troubleshoot receivers that have poor stereo operation and/or separation. To use the MPX signal: 1. Set the SG80 RF-IF MPX SIGNAL switch to the MPX. position. 2, Connect the 39G221 TEST LEAD to the SG80 andthe cireuit under test. 3. Set the AM & FM MPX MODE switch to STEREO. 4, Set the AUDIO switch to 1 kHz and the AUDIO MODULATION to 100%. 5. Adjust the RF-IF MPX VERNIER to match the circuit's signal level. Note: The RF-IF RANGE switch has no effect when using RF-IF MPX. FM-IF SWP ‘The sweep and marker test is becoming very popular not only as an alignment procedure, but as a troubleshoot- ing aid. Sweep tests on the IF can be used to isolate defects tothe RF or IF stages, The SG80 provides a sim- plified process to quickly test and troubleshoot the alignment of the IFs. ‘The alignment of FM Stereo tuners and receivers is critical, because the multiplexed FM stereo signal re- quires a greater bandwidth than an FM mono signal. ‘Touse the SWP signal for IF alignment/troubleshooting: 1, Set the RF-IF MPX SIGNAL control to the SWP position. 2. Connect one end of the 39G221 TEST LEAD to the RF IF MPX OUTPUT jack and the other end to the mixer input of the FM stereo receiver, 3, Connect the 39222 FM DETECTOR PROBE acces- sory to the SG80's FROMFM DETECTOR jack. Connect the VERT and HORIZ TO SCOPE jacks to the oscillo- ‘scapes vertical and horizontal inputs. 4, Select the vector mode on the ascilloseope. NOTE: Adjustment of the MARKER HEIGHT control will be required for viewing of the markers on the scope’s CRT. 5, For adjustment procedures, follow the tuner’s or re- ceiver’s service Yiterature or TROUBLESHOOTING section of this manual. AMRF The AM RF output is used to inject a signal with ‘monaural or composite stereo modulation, as selected by. the AM & FM MPX MODE switch, into the antenna input of AM receivers, The tuning range of the AM RF is from 520 kHz to 1720 kHz. You can push the RF-IF TUNING control to change the tuning speed from 10 kHz steps to 1 kHz steps. RF-IF MPX SIGNAL MPX — SWP Figure 11: Select the proper AM signal to match the circuit under test. ‘To use the AM RF output: 1. Set the SG80 RF-IF MPX SIGNAL ewitch to the AM RF position. 2. Connect the 75 ohm cable (39G220) to the RF-IF MPX, OUTPUT jack and the receiver under test. (Ifa 50 ohm connection is required, you should use the 396226 AM MATCHING PAD.) 3, Setthe AM & FMMPX MODE switch to STEREO, and the PILOT MODULATION control to the 100% level (pilot is not used in AM monaural). 4. Set the AUDIO switch to 1 kHz and the AUDIO MODULATION to 30%. 5. Adjust the REAP TUNING control to the desired output frequency. The frequency is displayed in the FREQUENCY LCD readout and automatically reads ‘kHz for AM signals. Each click of the RF-IF TUNING control changes the frequency by 10 kHz (the unit may power up in Fine or Course tuning steps). For 1 kHz steps, push the control knob once, To return to 10 kHz steps, push the control knob a second time.6. Foran output level of 65 dBf, adjust the RF-IF RANGE control to 60 dBf. Adjust the RF-IF MPX VERNIER for Babe NOTE: Remember to compensate for the marked output, level when using the 39G226 AM MATCHING PAD’s unbalanced output. Refer tothe Appendix section or pull chart for output levels. AMIF ‘The AM IF output is used to inject a signal with monau- ral or composite stereo modulation, as selected by the AM & FM MPX MODE switch, into the IF amplifiers of AM receivers. This signal is used for IF testing and ‘troubleshooting. The frequency is variable usingthe RF- IFTUNING control and has a range from 200 kFiz to 500 kizz ‘To use the AM IF signal: 1. Set the SG80 RF-IF MPX SIGNAL switch to the AM IF position, 2. Connect the 39G221 TEST LEAD to the RF-IF MPX OUTPUT jack and the cireuit under test. 3, Set the AM& FMMPXMODE switch to STEREO, and the PILOT MODULATION to the 100% level (the pilot is not used in AM MONAURAL). 4, Set the AUDIO switch to 1 kHz and the AUDIO MODULATION to 30%, 5. Adjust the RF-IF TUNING control to the desired output frequency. The frequency is displayed in the FREQUENCY LCD readout and automatically reads kHz for AM signals. When the unit is first turned on, bur LEVEL i - Figure 12: The SCA feature can be added to an FM signal by pressing the SCA button. The indicator light will be on If the SCA signal is being added. each click of the RF-IF TUNING control changes the frequency by 10 kHz (the unit may power up in Fine or Course tuning steps). For 1 kHz steps, push the control ‘knob once, To return to 10 kElz steps, push the contral knob a second time, 6.Foranoutputlevel of 65 dBf, adjust the RF-IFRANGE control to 60 dBF. Adjust the RF-IF MPX VERNIER for 5 BE SCA 67 kHz ‘The SCA 67 kHz function provides a factory set 67kHz output (adjustable internally from 53 kHzto 95 kHz), for testing SCA traps and SCA capable tuners and receiv. ers. The SG80 supplies the 2.5 kHz modulated SCA signal on either the FM RF, JF, or MPX positions of the RF-IF MPX SIGNAL control when the SCA indicator LED is lit. ‘To supply an SCA signal to the tuner or receiver: 1. Connect the 394220 test lead’s BNC connector to the ‘SG80's RF-IF MPX OUTPUT jack; connect the other end of the test lead to the receiver's test point, 2. Select the FM RF, IF, or MPX position on the RF-IF ‘MPX SIGNAL control, 3. Press the SCA button. If the SCA is on, the indicator LED will be lit. 4, Adjust the RF-IF MPX OUTPUT LEVEL controls to match the signal level required by the tuner or receiver. ‘75 uS PRE-EMPHASIS ‘The $G80 permits you to test the de-emphasis cireuitsin both tuners and receivers by supplying a pre-empha- sized signal. Most FM transmitted signals use the pre- emphasis of high frequencies to reduce noise. To test the audio de-emphasis circuits in a tuner or receiver, you need to compare a non-emphasized signal to one that has been emphasized. By monitoring the output signal level of the component under test and switching the 75 uS PRE-EMPHASIS button on and off, you will be able to see if the high frequencies are being , de-emphasized or not. NOTE: Some tuners and receivers will mute the ouiput with a modulation level in excess of 100% Always verify that the AUDIO MODULATION control is set for the proper level with the highest audio tone used.‘To use the 75 uS PRE-EMPHASIS feature: NOTE: To prevent over modulation, always set the percentage of modulation with PRE-EMPHASIS ON. 1. Setthe SG80 to produce a 65 dBf, 98.1 MHz, MONAU- RAL signal modulated 100% with 1 kHz audio. 2. Monitor the output of the component under test with an oscilloscope or level meter. Note: The output levels should be the same for 400 Hz, 1 kHz, and 5 kHz if the receiver's de-emphasis circuits are working. 3. Select the 5 kHz sine function with the AUDIO control, 4, Turn the pre-emphasis feature off by pressing the 75 uS PRE-EMPHASIS button. (The LED located on the left side of the button should not be lit.) 5. Note the signal level on the scope. 6. Press the 75 uS PRE-EMPHASIS button to turn it on. ‘You should see an inerease in high frequency signal level. wien, Septageatie’ go0Hs \ © a oF ® 7 75 pS PRE-EMPHASIS nt RE Figure 13: You can test the FM circults operation with both pre-emphasized signals. USING THE AUDIO DRIVE ‘The amplifier section of the receiver under test ean be tested by using the SG80’s AUDIO DRIVE section. Six aadio signals are selected with the AUDIO switch: 1) 400 Hix sine, 2) L kEz sine, 3) 5 kHz sine, 4) 400 Hz square, 5) L kHz square, 6) 5 kHz square. WwW ‘The three frequencies have matching sine and square- waves. Use the sinewave for testing noise and distortion, and the squarewave for checking frequency response. ‘The audio output level of the SG80 (0 to 3 VPP) is, controlled by the AUDIO DRIVE level control. The AUDIO DRIVE jack provides connection from the SG80 to the receiver under test, ‘AuDI0 MODULATION unio [ExT AUDIO IN ee AUDIO DAVE x Figure 14: Select the type ot audio signal to be used with the AUDIO control and set the level to match the circuit under test. To use the AUDIO DRIVE: 1. Set the $G80's AUDIO control to the desired fre- queney with either the sine or square waveshape. 2, Connect the 39G221 TEST LEAD to the AUDIO DRIVE jack and to the receiver under test. Connect to the point in the amplifier section of the receiver for the desired test. 3. Adjust the AUDIO LEVEL for the correct signal level, while monitoring the output of the reeeiver. ‘USING THE EXTERNAL MODULATION INPUTS ‘There may some instances where you will need a fre- ‘quency other than 400, 1000, or 5000 Hz, or if you wish, to perform a frequeney response test without using the computer interface. The SG80 provides EXT AUDIO IN jacks, which allow an external audio generator to modu- late both the AM and FM output. In order for the SG80’s AUDIO MODULATION control, tobe properly calibrated, you must supply a3 VPP signal from 30 Hz to 15 kHz. You may also supply different audio tonesto the LT and RT inputs, for intermodulation distortion and audible separation tests. /8 @ | tet {Ex AUDIO Ne h py ° oo Generator Figure 18: Connect an externat audio generator to modutate the SG80. ‘To supply the SG8O with an extemal audio signal: 1, Connect an external audio generator to the LT or RT or both inputs, 2, Set the external audio generator to supply a signal 3 ‘VPP and between 30 and 15600 Hz. 3, Select the EXT position of the AUDIO control. A, Use the G80 as normal.AUTOMATED BUS OPERATION Introduction ‘The SG80 AM STEREO-FM STEREO ANALYZER can be used for computer controlled automated testing. A simple program can control the front panel setup for automated performance testing. The SG80 can be used with either the IEEE-488 Bus or the RS232 formats, with the correct accessory connected to the INTER- FACE ACCESSORY JACK on the rear of the unit, NOTE: When using the G80 with the 1B72 IEEE 488 Bus Interface, check if EPROM IC4 is version 2.0. If your 1B72 has version 2.0, contact the Sencore Service Depart- ment for a replacement. ‘The SG80can be usedineither of two modes; the “talker” or the “listener”. ‘TALKER. The front panel settings of the SG80 ean be read by the controller. The controller must ask for the information in order for the SG80 to be used as a talker. Figure 16: The SG80 can be used for automatic testing ‘by connecting an interface Accessory anda computer’ controller. 19 LISTENER- A controller can be used to set the SG80's controls to any desired position, Youcan use the SG80in the listener mode to automatically set the SG80 to the standard signal format, tovary the settings to match the testing to be done, or both. CONNECTING THE SG80 TO THE INTERFACE BUS ‘The SG8O produces a special Sencore formatted signal which must be supplied to the interface accessory before it can be placed on the bus. The interface accessory, either the IEEE-488 or the RS233, is connected in series with the controller and the SG80. A standard cable is used for connection from the controller to the interface accessory. WARNING Connect only the Sencore interface bus accesso- ries to the INTERFACE ACCESSORY JACK on the rear of the SG80. Do not connect other instru- ments or interface bus equipment to the SG80 even if the connectors may fit. When using the SG80 with an IEEE-488 automated bus system, it must have an address in order for the control- ler to send and receive information. When using the G80 in conjunction with other products on the IEEE- 488 bus system, each instrament must have its own address separate from the other produets in the system. This allows the controller ta select which instrument it is talking or listening to. (Follow the individual instruc- tions for the controller and interface accessory for con- nection and address requirements.) WARNING Donotapply power tothe SG80 or interface acces sory until all connections have been made. To connect the SG80 to an automated test system: 1, Remove all power from the SG80, interface accessory, and the computer/controller.2 Set the slide switch on the rear of the IB72 IEBE-488 Bus Interface Accessory for the proper address assigned to the SG80. 3. Connecttthe interface accessory's male DIN connector to the INTERFACE ACCESSORY JACK located on the rear of the SG80. 4. Conneet the proper cable from the interface accessory to the controller. 6. Supply power to all units in the automated system, and verify all units have been tarned on, ‘USING THE SG80 AS A LISTENER, ‘The main operation of the SG80, in an automated test system, is that of a listener. The controller sends set- tings of the front panel controls to aid in performance testing and troubleshooting tuners and receivers. The controller can set all functions of the SG80 including setting the audio frequency in 100 hertz increments from 100 hertz to 15 kHz, The front panel contrels are automatically locked out (when the SG80 receives a command from the interface accessory) until a “CPO” (control panel on) command is received or the SG80 is turned off and back on. This prevents the SG80's controls from being varied acciden- tally duringa test, The SG80 will continue to produce an output while the controls are being set by the computer? controller, COMMAND DESCRIPTIONS ‘The SG80 uses an extensive series of commands to control the front panel setup. The entire command must be sent in order for the SG80 to properly respond. The following is a listing the control commands recognized by the SG80: LEARN Panel Setting Modulatio Panel Setting RF-IF Sig. Panel Setting SCA. Panel Setting FMK. Panel Setting Tuning Panel Setting Pilot Ma CPSPLM Panel Setting Audio Mod. CPSAUM Panel Setting Audio Signal CPSAUS Panel Setting Audio Level . CPSAUL Panel Setting Pre-emphasi Panel Setting All. 20 Freq Notation To Scientific. ‘Select RF FM Signal Select IF FM Signal Select Sweep IF FM Signal Select MPX FM Signal Select RF AM Signal. Select IF AM Signal .. ‘Tune Frequency Turn SCA On or Off. ‘Turn FMX On or Off. Set RF Range Set RF Level Vernier Set Pilot Modulation Set Audio Modulation .. Select Mono Modulation Select Stereo Modulation Select L+R Modulation Select L-R Modulation .. Select R Only Modalation. Select L Only Modulation Select Sinewave + Freq Select Squarewave + Freq Select External Source Turn Audio Of. Set Audio Drive Level ‘Set Audio Drive Level Invert Phas ‘Turn Pre-emphasis On or Off. Overall Level... Change Freq Only Change Waveshape To Square .. Change Waveshape To Sine... Where: aaa = E03, B06, kHz or MHz bbb = ON or OFF ece = UV or DBF or V xxx = Digits (1-6) The first group of commands is used by the controller to learn the settings of the SG80. These commands are also used if you want to store the settings for future compari- son or reference, CPO - Control Panel On- A CPO command is used to reset the SG80 for manual operation, If the SG80 does notreceivea CPO command, the front panel controls will not effect the SG80's operation. CPSALL - Panel Settings All-Send this command ifyou want the SG80 to send the settings of all the controls. Returns 10 lines of information.CPSAUL -Panel Setting Audio Level-'To read the level produced by the AUDIO DRIVE control, send this com- mand to the SG80. CPSAUM - Panel Setting Audio Mod- This command causes the SG80 to supply the percent of audio modula- tion being produced by the SG8O. CPSAUS - Panel Setting Audio Signal- When this command has been sent to the SG80 it will send the audio frequency and waveshape to the controller. CPSFMX -Panel Setting FMX-The CPSFMX command will cause the SG80 to send the status of the FMX button to the controller. CPSMOD - Panel Setting Modulation- When this com- mands sent from thecontrollerthe SG80 willreturn the setting of the AM & FM MPX MODE switch to the controller. CPSPLM - Panel Setting Pilot Mod- To read the pilot modulation level set on the SG80, send this command. CPSPRE - Panel Setting Pre-emphasis-This command allows the controller to receive the status of the 75 uS. PRE-EMPHASIS button. CPSRFT - Panel Setting Tuning- This command will return the frequency of the output signal from the SG8O, CPSSCA - Panel Setting SCA- The SG80 will send the status of the SCA button back to the controller when it receives this command. CPSSNG - Panel Setting RF-IF Sig- This command will cause the SGB0 to send the position of the RF-IF MPX SIGNAL control back to the controller. The following commands are used for setting the front panel controls to a desired position to produce the correct, output. ALF - Freq Notation To Alpha- The ALF command places the SG80 inte the alpha-numeric frequency mode to match your controller. The SG80 can receive fre- quency input in either the alpha-numeric or scientific notation formats, but will output in the alpha-numeric format only. AULxx.xx - Set, Audio Drive Level- To set the audio drive level send this command. The xx.xx represents the ‘evel you wish to output. Add a minus sign to change phase, for example: AUL -x.20% AUMaxxx-Set Audio Modulation-The audiomodulation level is set by sending the AUM command followed by the level. 21 AUSxxxxxx - Change Freq Only-To change the audio frequency only end this command. AUSxxxxSIN - Select Sinewave + Freq- To set a sine- wave audio frequency on the SG80 you should send the AUS and SIN portion. The x0cxx represents the desired frequency. AUSxxxxSQR - Select Squarewave + Freq- You can cause the SG80 to produce a square wave with the desired frequency by sending this command. AUSEXT - Select External Source- This command will use the EXT AUDIO IN signal as the audio source. AUSSIN - Change Waveshape- This command changes the audio waveshape to the sinewave. AUSOFF - Turn Audio Off: This command turns the audio off. AUSSQR - Change Waveshape-This command changes the audio waveshape to the squarewave. DBF - Output Level To DBF- This command will place the output in the dBf format. EXP. Freq Notation To Scientific-This command places, the SG80’s frequency in the scientific notation mode to match your controller. The SG80 can receive frequency input in either the alpha-numeric or scientific notation, formats, but will output in the scientific notation format only, FMXbbb - Turn FM n or Off- This command changes the status of the FMX button. The FMX portion of the command seleets the FMX button and the bbb changes the state, MODLER - Select L+R Modulation- You can put the SG80 in the L+R modulation mode by sending this command, MODLER - Select L-R Modulation. To produce a LR ‘modulated signal with the SG80, send this command from your controller. MODLCH - Select L Only Modulation- This command causes the SG80 to produce an output signal with left only modulation, MODMON - Select Mono Modulation- This comma selects mano modulation of the output signal from the G80. MODRCH - Select R Only Modulation- This command will cause the SG80 to produce an output signal with right only modulation,MODSTR- Select Stereo Modulation - To select stereo modulation send this command to the SG80. PLMaxxx - Set Pilot Modulation- To set the pilot modu- lation, send PLM followed by the percent of pilot you wish the SG80 to produce, ‘PREbbb~Turn Pre-emphasis On or Off- This command turns the 75 uS PRE-EMPHASIS either ON or OFF as directed, RFLxxxxxxcce - Overall Level- This command can be used to replace the individual commands to the range and vernier output level, by setting both in one com- mand. RFT - Tune Frequency- By sending this command followed by a frequency in either alpha-numeric or scientificnotation, the SG80 will automatically tune the output to that frequency. RFVxxxxxxcee - Set RF Level Vernier. Send this ‘command to fine adjust the output level produced by the G80. RNGxx - Set RF Range- You can set the RF output level range by sending the RNG command. The additional information tells the SG80 which range. SCAbbb - Turn SCA On or Off- The SCA part of this command selects the SCA button, and the bbb part causes the SCA circuits to turn ON or OFF. SIGAMI - Select IF AM Signal- The AM IF signal is produced when the SG&0 receives the SIGAMI com- mand. SIGAMR--Select RF AM Signal-The SG80 producesthe AM RF signal when it receives this command. SIGFMI - Select FM IF Signal- This command places ‘the SG80 in the FM IF signal format. SIGFMR - Select FM RF Signal- This command places the SG80 in the FM RF signal format. SIGMPX<-Select FMMPXSignal-Thiscommand causes the SG80 to produce the MPX format signal. SIGSWP - Sclect Sweep FM IF Signal- When the SG80 receives this command it will output the sweep signal used for sweeping the IPs. UVT- Output Level To UV-By sendingthis command to the SG80 the output level is in microvolts. NOTE: Refer to the instructions for the controller in your ‘system to verify the commands listed can be used in this alpha numeric format. Most systems will require the information in a “string variable” that becomes part of a “Print” statement, & “Write” statement, or a subroutine call. ERROR CODES If the SG80 receives an invalid command it will return an error code, The code can be triggered by an erroneous frequency, bus command, or level. The following section ists each of the error codes and provides a brief deserip- tion of each. E0- Valid command has been processed. EL. Frequency beyond range of signal selected. Example: sending “RFT120 MHZ” after an “AMI” command sending any “RFT” command after an “MPX° conimand, sending an “RFT” 150000 Hz” command E2- Invalid bus command. Example: other than “on” or “o®” with “SCA x” command. code that is not an SG80 bus command, E3- RF-IF level beyond range of anit. Example: entry other than 0,2,4,6,8, or 10 in “RNG x commend; entry larger than 20 in “RFV xx” command; entry less than 0 of larger 120in “RFX” command EA. Modulation beyond range of unit, Example: entry less than 0 or larger then 125 in “PMO x” command; entry less than 0 ot larger than 100 in “AMO x” command; ece other than MON, L4R, RON, LON, “MOD eee”; AUM less than pilot setting. E5- Audio signal beyond range of unit. Example: frequency less than .1 in “AUD ece sexx” command; frequency larger then 20 in “AUD cee xx.x” command; level greater than 3.00 in “ADL, xox” command, E6- Function not allowed in signal selected by RFAF signal select. ‘USING THE SG80 AS A TALKER/ LISTENER ‘The SG80 can be used as a talker/listener to control and store the front panel settings for later or special use. The12345678910 RFIIF Signal $1 @-----=-- SCA Setting $C A-------- $C A>------- XRF Setting KR FO- HHH XR FO------- Frequency (Default) R F T—~———~—— 1 (Default) R FT -——--——-— RFT-—------- RFT-------- (Default) R F T~—~--~-~--— (Default) RF T-—-~—--~--— RF T-—------- RFT-------- RF Levet RF LO ----— + RFL-—------— Pilot Mod Level =P MO —~——~—~—-——— Audio ModLevel =A MO —————~—~— MPX Modulation =m 0 0 -—~—~-~—~~—— Audio Signal AUS—-—-------— AYS——------- AU S———-----— Audio DriveLevel A UL —~—~—--~-—-~~ Pre-emphasis pPRE-—-----~-— pRE-—---~---— 11 12 19 14 15 16 17 18 19 20 21 22 ------- -- FMR ----------0ON ------- -- OFF ----- er KH KCN —--------- OFF o4 oo E+ 08 ~HZ 98 10 E+ 06 —HZ --- 101 00 MHZ ----98.10MHZ — tt 008+ 03 -HZ —--7 80 E+ 03-HZ —----- 11 00K HZ ------7 80K HZ --- 273000-uUvY --7>-- 1 12 0B F --- - rH t 00H % ------- 61 --% ------- -- LR ----- 1000 8 1 N ------40080R ------- HT EXT --- 2758 --Vv —----------oN ------- HOFF Figure 17: This is the data format sent to the computer from the SG80. commands discussed earlier can be used to set the SG80 to a set standard, then by sending a CPO command, manual operation can be restored to the SG80. When the special test set-up is complete, you can read the front panel and store the information: ‘The SG80 lets you read the front panel controls all at, lonee, or one at a time. By sending one of the individual feature commands, the controller ean read that. contrel. By sending the Panel Setting All command, all front panel settings will be read, Your controller must be able to receive 10 data fields, one after another with a CR or LF between them. Figure 17 shows the data field format sent from the SG80. The data fields 23 characters longandis followed by a carriage return or line feed. The first 3 characters represent the SG80 control. These are followed by 17 spaces used for numeric position representation, ‘The final 3 characters identify the status of the control, or they may be used as annaneiators.APPLICATIONS NTRODUCTION ‘he SG80 is a patented analyzer that does a complete ab of servicing any AM-FM or new AM Stereo receiver, rom the lowest to highest priced, faster and more ecurately than ever before. Tis the only instrament, hat combines an AM and FM generator into one unit, aking the signals look similar, even though they are ntirely different. This greatly simplifies the operation f the analyzer and reduces your chance of costly errors. tis the only tester that has signal injection trou- ‘leshooting capabilities to isolate any problem to the unetional section of the receiver. The SG80’s superior pecifications enable top notch performance tests of all \M-FM receivers to manufacturer requirements assur- ag you the job was done right. che APPLICATIONS section has been split into two lifferent categories for your convenience, PERFORM- \NCE TESTING, and TROUBLESHOOTING. For a isting of categories within each section refer to the ollowing table of contents. “he following application section covers many of the ommon uses of the SG80. All procedures covered in his section are generic and designed to work with all uners and receivers. YOTE: The following test are performed at a midrange uning frequency. For complete testing of tuners and eceivers you should repeat the test procedures at three ‘laces within the tuning range, low, middle, and high. NDEX *ERFORMANCE TESTING OF FM TUNERS/ ECEIVERS Using Standard FM Input Reference Signal: 50 dB Quieting Sensitivity .. FM Signal-To-Noiss FM Sterco Separation... FM Mating Threshold 29 FM Stereo Switching Threshold.. 30 FM Stereo Pilot Detect Sensitivity “31 FM SCA Rejection .. 32 FM Receiver Audio Frequency Respons 33 FM Receiver Distortion Test... : FM Automatic Seek Level Test 24 PERFORMANCE TESTING AM MONO AND STEREO TUNER/RECEIVERS Using A Standard AM Mono And Stereo Setu AM Tuning Range and Indieator Accuracy .. ‘AM Usable Sensitivity Test, ‘AM Signal-To-Nois ‘AM Adjacent Channel Selectivity . ‘AM Automatic Seek Level.. AM Receiver Distortion ‘AM Stereo Separation... AM Receiver Audio Frequency Response. FM STEREO RECEIVER TROUBLESHOOTING AND ALIGNMENt DETECTOR - STEREO DECODER ‘Testing the FM Detector. Identifying Defective FM Decoder Stages Signal Injection Into Audio Stages Adjusting FM Stereo Separation Adjusting FM SCA Traps IP AMPLIFIERS Identifying Defective FM IF Stages... Peak Align FM IF Stages Sweep Test and Align IF Stages ‘TUNER SECTION Identifying Defective FM RF/Mixer Stages ......53 Adjusting FM Tuning Range . 54 Adjusting Auto-Seek Circuits AM STEREO RECEIVER TROUBLESHOOTING AND ALIGNMENT DETECTOR - STEREO DECODER ‘Testing AM Detector Stage .... Identifying Defective AM Stereo Decoder Stage Adjusting AM Stereo Separatio IP AMPLIFIERS Identifying Defective AM IF Stages.. AM IF Alignment ‘TUNER SECTION ‘Identifying Defective AM RF/Mixer Stages Adjusting AM Tuning Range..PERFORMANCE TESTING OF FM TUNERS/RECELVERS USING STANDARD FM INPUT REFER- ENCE SIGNALS For the majority of the FM tuner/receiver testing and servicing, you will be required and want to start with a point on many ofits recommended tests. The follow- Standard input signal, The IEEE/IHF Fn receiver test ing listing explains how to set the SG80 to produce standards uses a standard signal format as a starting the standard output signal format for FM mono and Stereo testing. SENCCRS red wore ap 100. [FM ANT————art ANT- oT mana sy ie : Auoio out E ce e al gz s 5 2 s <7 I<} es a a = a Es Z is oS 2 eae = = 29 we Raa TET w ‘To et the S080 to produce standard EM mono To set the SG80 to produce an FM Stereo output: signal: " 1, Connect the SG80's RF-IF MPX OUTPUT jeck 1. Connect the SGE0's RF-IP MPX OUTPUT jock to to the antenna terminals ofthe tuner/receiver See ee Sees Re MT OUTPUT jerk under test, (Ifthe receiver has selectable IF receiver has selectable IF bandwidths, set it to the bandwidths, st it to the widest mode.) receiver has 2. Select the FM Stereo mode on the tuner! 2 Beate Toate 1380 control; receiver; set its tuner to 98.1 MHz PRP IPMEX ONAL Oo he FM RF positon. 3, Set the SG80's controls as follows: B. RF-IF OUTPUT LEVEL to produce a 65 dBF A. REAP MPX SIGNAL to FM RE. epee. B.RF-AP OUTPUT LEVEL controls for 65 ©. Ensure SCA is turned off abr. D. RF-IF TUNING control 0 98.1 MHz. ©. Ensure SGA is off E. AM & FM MPX MODE to MONAURAL. D. REP TUNING for 98.1 Miz FAO AMEX MODE to MC E, PILOT MODULATION for 100% NORMAL. G. AUDIO MODULATION to 100%. EAU TEE ODE te STEREO 3. Set the tunerireceiver to 98.1 MHz. BARRIO te A ne sine. H. AUDIO MODULATION for 100%, 850 dB QUIETING FM SENSITIVITY The 50 dB quieting sensitivity specification of tuners and receivers is used to identify the relative freedom from internal noise when a iow signal level is received. This noise is most noticeable during pauses in modula, tion, when the tuner/receiv with modulation, The sensitivity requirements are similar to that of signal-to-noise (S/N) testing, but is referenced to the input signal level, is not masking the noise G 39072 75-300 MATCHING TRANS. POWER: RMS VOLTS == & =] LBRBD momma | 18.10 BRBS MIA Left wna "RMS VOLTS To test the 50 dB quieting sensitivity of a FM tuner! receiver: 1. Set the SG80 and receiver according tothe "Using Standard Input Reference Signals" section on page 25. 2. Measure the receiver's output in RMS volts or dBm, 3. Set the AUDIO control to the OFF position and again measure the output of the tuner/receiver. 26 Right / 4, Calculate the S/N ratio with the following formula: dB =20 log rms step 2/rms step 3, or subtract step 3 from step 2 if using dBm. If the SIN ratio is greater than 50dB reduce the ‘$G80's RF level and repeat steps 1-4. The level at which a 50 dB SIN is obtained is the 50 dB quieting sensitivity.FM SIGNAL-TO-NOISE One of the problems with FM tuners and receivers is that of noise, Because of the higher frequencies and ‘more complex cireuitry, FM Stereo reproduction is more susceptible to noise then mono. Of all the problems that, can affects the quality of FM reception, noise is the most bothersome to listeners, The SG80 provides a quick test of the signal-to-noise capabilities of FM tuners and receivers, ‘This test is done on FM mono and Stereo tuners and receivers, using a standard input signal level of 65 dBF. ‘The test compares the output level when there is modulation end when there is no modulation (noise). In the mono mode, most tuners and receivers should produce 70 to 90 dB SIN. In the stereo mode you may see 60 to 80 dB. SENCOR= 3972 75-300 MATCHING TRANS. To measure the SIN ratio of a tunerireceiver with the SG80: 1, Set the SG80 and the receiver according to the “Using Standard Input Reference Signals” section on page 25. 2, Measure the receiver's outgut in RMS volts or dBm, 3. Turn the AUDIO control to the OFF pasit RMS VOLTS POWER TURING. [w RRS LEFT mame [18-10 | SO MA | (ie reves) “cs: OS RMS VOLTS. RIGHT measure the receiver’s output RMS volts. 4, Caleulate the S/N ratio with the following formula: 4B = 20 log RMS step 2/RMS step 3, or subtract step 3 form step 2 when using dBm.FM S1EREO SEPARATION Separation is a test to see how much of the left chan- nel’s signal inside the tuner/receiver crosses over into the right channel, or vise versa, when a stereo format signal is being received. Specifications on separation for different tuners/receivers will vary dramatically. Most tuner/receivers typically give the highest separation when supplied with a 1 kHz sinewave. ‘When testing separation with the SG80, you will supply either a "Right or Left ONLY" signal and measure the difference between the right and left output levels. Most ttuners/receivers specify the separation in decibel form, s0 an output monitoring meter should be able to direetly display decibels. 39072 75-900 MATCHING TRANS. RMS VOLTS y LEFT rues =f mF DPDBD_p e cmpaememe [18.10 | SESRSECR | [WAI RMS VOLTS To measure separation with the SG80: 1, Sot the SG80’s controls to produce the FM Stereo standard signal format discussed earlier in the " Using Standard Input Reference Signals" section on. page 25. 2, Select the R ONLY position of the AM & FM MPX. MODE control. 3. Compare or calculate the difference in the left and 28 right output of the tuner/receiver under test. This is the right to left separation. 4, Select the L ONLY position of the AM & FM MPX, ‘MODE control 5. Compare or calculate the difference in the left. and right output of the tuner/receiver under test. This is tthe left to right separation.