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Broadcast Electronics Marti Electronics ME-40 Manual Download Page 73

63 

 

 

 

©2011 Broadcast Electronics 

WARNING 

DISCONNECT THE POWER FROM THE EXCITER BEFORE REMOVING OR REPLACING ANY 

COMPONENTS. 

WARNING 

 

 
 
 

 
 

CAUTION 

INADVERTENT CONTACT BETWEEN ADJACENT COMPONENTS AND CIRCUIT TRACES MAY 

DAMAGE THE RF AMPLIFIER ASSEMBLY. 

CAUTION 

 
 

 
 
 

After the problem is isolated and power is totally deenergized, refer to the schematic diagrams 
and the theory of operation to facilitate in problem resolution. The defective circuitry may be 

repaired locally or the circuit board may be returned to Marti Electronics for repair or replacement 

 

 

Summary of Contents for Marti Electronics ME-40

Page 1: ...dcast Electronics 4100 North 24th Street Quincy Illinois 62305 USA Phone 217 224 9600 Fax 217 224 9607 www bdcast com bdcast bdcast com Marti Electronics FM Exciter MODELS ME 40 566 017 rev D April 4...

Page 2: ...tronic or mechanical including photocopying or recording for any purpose without the express written permission of Broadcast Electronics Trademarks Broadcast Electronics and the BE logo are registered...

Page 3: ...component defects or performance concerns on components that have been soldered installed wired or in any way altered from new their new condition d Resale Equipment defined as equipment purchased fr...

Page 4: ...e are no third party beneficiaries of any of the provisions of this warranty If the equipment is described as used equipment it is sold as is and where is and no warranty applies unless authorized in...

Page 5: ...ce is available from Broadcast Electronics by letter prepaid telephone or E mail Equipment requiring repair or overhaul should be sent by common carrier prepaid insured and well protected If proper sh...

Page 6: ...ompt issuance of credit Please furnish complete details as to circumstances and reasons when requesting return of merchandise All returned merchandise must be sent freight prepaid and properly insured...

Page 7: ...tubes and power transistors involves one or more of the following hazards any one of which in the absence of safe operating practices and precautions could result in serious harm to personnel A HIGH V...

Page 8: ...h hour average level has been adopted by several U S Government agencies including the Occupational Safety and Health Administration OSHA as the standard protection guide for employee work environment...

Page 9: ...ON 14 4 1 POWER SUPPLY CONTROL CIRCUITS 14 4 2 RFI FILTER NETWORK 14 4 3 METERING CIRCUIT 15 4 4 AFC PLL CIRCUIT 15 4 5 MODULATED OSCILLATOR CIRCUIT 15 4 6 RF AMPLIFIER ASSEMBLY 15 5 MAINTENANCE 16 5...

Page 10: ...viii 2011 Broadcast Electronics...

Page 11: ...omposite inputs from a stereo generator or SCA generator in addition to a 600 Ohm balanced monaural input Typical performance exhibits extremely low distortion with THD and IMD less than 0 05 and a ty...

Page 12: ...requency Stability 500 Hz 32 F to 122 F 0 C to 50 C Modulation Type Direct FM at the Carrier Frequency Modulation Capability 300 kHz Modulation Indication Peak Reading Color Coded LED Display with Bas...

Page 13: ...38 Pounds 17 2 kg 5 25 Inches 13 3 cm 17 70 Inches 44 9 cm 19 00 Inches 48 3 cm ENVIRONMENTAL Ambient Operation Temperature Humidity Altitude 0 C to 50 C 95 Maximum Non Condensing 7500 ft 50 Hz 2286M...

Page 14: ...igure 2 1 and ensure the appropriate primary AC line voltage is visible on the AC LINE VOLTAGE SELECTOR circuit board 100V 115 120V 220V or 230 240V 4 If an alternate AC line voltage is required remov...

Page 15: ...5 2011 Broadcast Electronics...

Page 16: ...1 POS MUTE NEG switch S3 on the power supply control circuit board is provided to select the RF mute input logic polarity refer to Figure 2 2 S3 must be in the POS position when the ME 40 is operated...

Page 17: ...NING 2 4 2 WIRING Refer to Figure 2 1 and connect a coaxial cable located in the accessory kit between the RF OUTPUT connector on the exciter rear panel and a 50 Ohm RF load capable of dissipating the...

Page 18: ...data sheets for the correct indication 4 Rotate the TEST METER switch in Reverse Power position The meter should read near zero watts assuming a perfect 50 ohm resistive load is connected to the exci...

Page 19: ...d on the rear panel of the ME 40 Each input is AC coupled and accepts frequencies from 40kHz to 100kHz An input of 3 5V P P 1 24 VRMS will modulate the FM carrier 10 at 7 5 kHz When using an SCA input...

Page 20: ...erating procedures 3 1 CONTROLS AND INDICATORS Refer to Figure 3 1 for the location of all controls and indicators associated with normal operation of the ME 40 Exciter The function of each control or...

Page 21: ...e divide the Test Meter reflected power indication by the Test Meter forward power indication Locate the quotient in the POWER RATIO column The VSWR is listed across from the POWER RATIO entry 3 2 2 T...

Page 22: ...elected Lower scale refer to 11 LOCK Status Indicator Illuminates to indicate the operating frequency is stabilized 12 VSWR Status Indicator Illuminates to indicate reflected power exceeds 5 5 watts 1...

Page 23: ...13 2011 Broadcast Electronics...

Page 24: ...ains over voltage over current reverse voltage short circuit and over temperature circuitry to protect the exciter sub assemblies 4 1 2 CONTROL CIRCUIT The control circuitry regulates operation of the...

Page 25: ...udio with AFC tuning bias which linearizes the modulation and adjusts the carrier frequency of the modulated oscillator 4 5 MODULATED OSCILLATOR CIRCUIT The modulated oscillator circuit generates the...

Page 26: ...Y POWER IS DISCONNECTED FROM THE EXCITER BEFORE ATTEMPTING EQUIPMENT MAINTENANCE WARNING 5 2 FIRST LEVEL MAINTENANCE First level maintenance consists of precautionary procedures applied to equipment t...

Page 27: ...it F RF Amplifier G Control Circuit H Exciter Output DC VOLTMETER Use an external high impedance voltmeter to measure internal DC potentials Refer to Figure 5 1 and the following procedure Procedure t...

Page 28: ...VDC 7 8 VDC 8 9 VDC 8 5 VDC 10 7 VDC 12 1 VDC 11 8 VDC 13 4 VDC 15 0 VDC 14 8 VDC 18 9 VDC 20 3 VDC 20 6 VDC 88 1 MHz 98 1 MHz 108 1 MHz 1 10 Amperes 0 97 Amperes 1 00 Amperes 1 59 Amperes 1 40 Ampere...

Page 29: ...trace can be destroyed by excessive heat or lateral movement during soldering Use of a small iron with steady pressure is required for circuit board repairs To remove a soldered component from a circu...

Page 30: ...om the socket 5 7 EXCITER PREPARATION FOR SHIPMENT If the exciter is removed from service to be shipped to another location ensure the following steps are accomplished prior to shipping a Secure the m...

Page 31: ...wer supply is full wave rectified filtered and electronically regulated to assure stable equipment operation Refer to Table 5 3 for electrical characteristics relative to the power supply control circ...

Page 32: ...r 5 9 2 DETAILED THEORY OF OPERATION Power Supply Control Board This section presents the theory of operation for the exciter power supply control circuit board The power supply control circuit board...

Page 33: ...inverting input of voltage regulator U4 through S1 and D1 and the non inverting input of U2A which operates as a comparator circuit If the reflected power level at U2A non inverting input exceeds the...

Page 34: ...in the external position a reference voltage can be applied to PWR SET control R52 through the rear panel external power level control connection to control power externally Automatic Power Control Op...

Page 35: ...R78 adjust the output of U6 for a regulated 20 volt DC potential The supply is applied to the AFC PLL circuit board and metering circuit board 4 20 VOLT SUPPLY The 25 0 volt AC potential is routed to...

Page 36: ...26 2011 Broadcast Electronics FIGURE 5 1 POWER SUPPLY SIMPLIFIED SCHEMATIC DIAGRAM...

Page 37: ...Cable BNC connectors shipped with exciter P N 947 0020 Calibrated 50 Ohm in line wattmeter Digital voltmeter Fluke 75 or equivalent Temperature probe Fluke 80T 150 or equivalent FWD CAL R5 AND RFL CA...

Page 38: ...PWR SET control R52 for a 40 watt output power indication on the external meter g Refer to the figure and adjust FWD CAL control R5 for 40 watts as indicated on the front panel FWD meter h Remove the...

Page 39: ...29 2011 Broadcast Electronics Figure 5 3 PARALLEL LOAD CONNCTIONS...

Page 40: ...NY COMPONENT WITHIN THE EXCITER WITH POWER APPLIED WARNING m Refer to Figure 5 2 and adjust PWR SET control R52 until the meter indicates the value recorded in step A WARNING DISCONNECT THE PRIMARY PO...

Page 41: ...TP6 ground f Apply primary power to the exciter WARNING DO NOT TOUCH ANY COMPONENT WITHIN THE EXCITER WITH POWER APPLIED WARNING g Refer to the figure and adjust TEMP CAL control R25 until the voltmet...

Page 42: ...R APPLIED WARNING d Refer to Figure 5 2 and adjust R27 until the voltmeter indicates 3 65V DC WARNING DISCONNECT THE PRIMARY POWER TO THE EXCITER BEFORE PROCEEDING WARNING e Disconnect the primary pow...

Page 43: ...PONENTS AND CIRCUIT TRACES MAY DAMAGE THE POWER SUPPLY CONTROL CIRCUIT BOARD CAUTION After the problem is isolated and power is totally de energized refer to the schematic diagrams and the theory of o...

Page 44: ...34 2011 Broadcast Electronics FIGURE 5 4 NO PA VOLTAGE TO THE RF AMPLIFIER...

Page 45: ...p Nominal with 2 0V to 9 0V DC Dependent on the RF Center Frequency 1 mW at 50 Ohms 1 mW at 50 Ohms 5 10 1 REMOVAL AND INSTALLATION This section provides removal and installation procedures for the mo...

Page 46: ...chematic diagram of the modulated oscillator circuit board Refer to Figure 5 5 as required for a description of the following circuits Modulator Oscillator Buffers and Output Amplifier Power Supply 5...

Page 47: ...37 2011 Broadcast Electronics FIGURE 5 5 MODULATED OSCILLATOR SIMPLIFIED...

Page 48: ...ch establish a 50 Ohm output impedance Two identical signals are output from the modulated oscillator assembly The signal at R24 provides drive to the RF amplifier and the signal at R23 provides a fre...

Page 49: ...lectronics Figure 5 6 Modulated Oscillator Assembly 5 11 AFC PLL The AFC PLL circuit board I synthesizes and maintains the desired carrier frequency to a high degree of precision and 2 processes the a...

Page 50: ...oscillator Refer to the table for electrical characteristics relative to the AFC PLL circuit board TABLE 5 5 ELECTRICAL CHARACTERISTICS AFC PLL Circuit Board PARAMETER SPECIFICATIONS INPUTS RF SAMPLE...

Page 51: ...follow the REMOVAL PROCEDURE in reverse order 5 11 2 DETAILED THEORY OF OPERATION AFC PLL Circuit Board The AFC PLL circuit board contains nine circuits simplified schematic of the AFC PLL circuit boa...

Page 52: ...e a frequency of 500 Hz When binary switches S1 S2 and S3 are preset for the appropriate carrier frequency U9 will divide the RF sample signal at the F input to provide 500 Hz at the FV output which i...

Page 53: ...DRIVER The LOW output from U13A is routed to a dual rate control network consisting of R42 R43 C44 and D3 This circuit is identical in operation to the slow charge rapid discharge circuit previously...

Page 54: ...A through balanced monophonic level control R91 UNBALANCED INPUTS Subcarrier audio from rear panel connectors SUB1 SUB2 and SUB3 and audio from front panel composite test connector are input to U10A t...

Page 55: ...R91 is adjusted as follows Procedure to adjust BAL MONO control R91 refer to the figure as required and proceed as follows WARNING DISCONNECT PRIMARY POWER TO THE EXCITER BEFORE PROCEEDING WARNING a...

Page 56: ...OMP level control on the AFC PLL circuit board adjusts the output level of the unbalanced composite amplifier circuit UNBAL COMP control R69 is adjusted as follows Procedure to adjust UNBAL COMP contr...

Page 57: ...ITHIN THE EXCITER WITH POWER APPLIED WARNING d Apply primary power and operate the exciter e Adjust the audio generator for 400Hz at 2 12V RMS output as indicated on the voltmeter f With an insulated...

Page 58: ...ollowing WARNING DISCONNECT PRIMARY POWER TO THE EXCITER BEFORE PROCEEDING WARNING a Disconnect the exciter primary power b Remove the exciter top cover and connect a frequency counter to TP1 on the A...

Page 59: ...49 2011 Broadcast Electronics TABLE 5 6 FREQUENCY SYNTHESIZER PROGRAMMING...

Page 60: ...to the Table and select the desired frequency and corresponding binary code c Refer to Figure 5 7 and program four segment switches S1 S2 and S3 for the desired frequency d Replace the top cover and...

Page 61: ...oting philosophy for the AFC PLL circuit board consists of isolating a problem to a specific circuit The problem may be further isolated by referencing the following information and Figures 5 8 and 5...

Page 62: ...52 2011 Broadcast Electronics FIGURE 5 8 NO RF OUTPUT LOCK IS EXTINGUISHED...

Page 63: ...llator to an adjustable level of 3 to 50 watts as required to drive an associated transmitter Directional coupler sensing lines on the circuit board provide both forward and reflected power outputs fo...

Page 64: ...ORE PROCEEDING WARNING a Disconnect the primary power from the exciter b Remove the exciter top cover and disconnect J15 from PI5 of the RF amplifier power control cable c Disconnect BNC connector P18...

Page 65: ...ains forward and reflected power directional couplers and an input mute circuit The directional coupler outputs and operating potentials are routed from the circuit board through the chassis with feed...

Page 66: ...56 2011 Broadcast Electronics FIGURE 5 10 RF Amplifier SIMPLIFIED SCHEMATIC...

Page 67: ...e step up transformer to establish an output impedance of 50 Ohms and 2 a second harmonic notch filter Capacitor C36 functions as a DC blocking capacitor Power amplifier Q4 operates from an adjustable...

Page 68: ...k for test load P N 417 3841 coaxial accessory cable BNC connectors shipped with exciter P N 947 0020 5 12 3 1 RFL NULL R12 The RFL NULL control on the RF amplifier circuit board adjusts the directivi...

Page 69: ...ace the access hole plug and exciter top cover 5 12 3 2 PA BIAS R17 PA BIAS control R17 on the RF amplifier circuit board adjusts the PA quiescent current Potentiometer R17 is adjusted as follows WARN...

Page 70: ...DJUSTMENT WARNING i Remove RF drive by disconnecting P17 from the RF amplifier j Refer to Figure 5 11 and adjust PWR SET control R52 on the power supply control circuit board fully clockwise k Depress...

Page 71: ...er assembly in the exciter chassis 5 12 4 TROUBLESHOOTING The troubleshooting philosophy for the RF amplifier assembly consists of isolating a problem to a specific circuit The problem may be further...

Page 72: ...62 2011 Broadcast Electronics Figure 5 11 RF Amplifier Circuit Board Controls...

Page 73: ...ENT COMPONENTS AND CIRCUIT TRACES MAY DAMAGE THE RF AMPLIFIER ASSEMBLY CAUTION After the problem is isolated and power is totally deenergized refer to the schematic diagrams and the theory of operatio...

Page 74: ...64 2011 Broadcast Electronics This page intentionally left blank...

Page 75: ...DISCONNECT 18 22 2 1 410 155 LED Red rectangular 604 L113HDT 2 1 410 255 LED Green rectangular Lumex SSL LX2573GD 1 1 415 1010 FUSE CLIP LITTLEFUSE 101002 2 1 417 0017 RECP BNC BULKHEAD UG 492A U 1 1...

Page 76: ...2 1 469 0365 1 STRIP RFI SHIELD 2 2 469 0365 FINGER STOCK 1S197520A 2 75 1 469 0366 1 STRIP RFI SHIELD 1 25 4 2 469 0366 FINGER STOCK NOTE 1 25 1 469 0366 2 STRIP RFI SHIELD 4 25 6 2 469 0366 FINGER S...

Page 77: ...5K SINGLE TURN VERTICAL PCB MOUNT 3 2 145 390 Resistor 39 ohm 1 4 watt 5 carbon comp 30BJ250 4 2 145 431 Resistor 432 ohm 1 4 watt 1 metal film Mepco SFR25 1 2 185 000 Resistor 0 Ohm 1206 Chip Mfg DA...

Page 78: ...EGRATED CIRCUIT SANYO LB1412 NOTE 1 IC1 3 411 225 LED BAR GRAPH DISPLAY LUMEX SSA LXH1225 23707 1 D1 D12 3 500 120 Eyelet 1 544047 5 copper 2 3 550 206 Connector bottom entry Molex 22 14 2034 OR 22 17...

Page 79: ...15K OHM 1 4W 1 4 R25 R26 R27 R51 2 100 1731 RES 174 OHM 1 4W 1 1 R59 2 100 2723 RES 27 OHM 1 4W 5 1 R34 2 100 3031 RES 301 OHM 1 4W 1 1 R57 2 100 3951 RES 39 2K OHM 1 4W 1 1 R9 2 100 4773 RES 4 7MEG O...

Page 80: ...175 1034 RES TRMR 1K VERT ADJ 1 R63 2 177 5044 RES TRMR 5K VERT ADJ 3 R69 R81 R91 2 177 5054 RES TRMR 50K VERT ADJ 1 R52 2 200 0009 DIODE ZENER 1N 4739A 2 D17 D19 2 203 4005 DIODE 1N4005 2 D16 D18 2...

Page 81: ...4 PCB BLANK AFC PLL scan 1 2 700 0148 TAPE JOINING 3 4 0 001 2 949 1050 001 ASSY CABLE AFC PLL SBCM 1 3 402 0051 TY RAP W FLAG 1 3 418 0034 PLUG BNC DUAL CRIMP 1 227079 6 1 3 621 1359 CBL COAX RG316 U...

Page 82: ...1 4W 1 METAL 1 R39 3 103 3324 RES 3 32K OHM 1 4W 1 METAL 1 R29 3 103 3325 RES 33 2K OHM 1 4W 1 METAL 3 R35 R40 R48 3 103 3631 RES 365 OHM 1 4W 1 METAL 1 R75 3 103 3924 RES 3 92K OHM 1 4W 1 METAL 2 R1...

Page 83: ...2 E3 E4 E5 E6 E7 E8 3 413 0106 TERM TEST POINT OVAL RED 8 TP1 TP2 TP3 TP4 TP5 TP6 TP7 TP8 3 415 2068 CLIP FUSE 15AMP LITTLEFUSE 1020 71 2 XF1 XF2 3 417 0003 CONN HEADER 3 PIN 1 J22 3 417 0169 CONN 15...

Page 84: ...2 002 1034 CAP CER DISC 001UF 1000V 3 C301 C302 C303 2 003 1054 CAP CER MNLY 1uF 50V 20 8 C304 C305 C306 C307 C308 C309 C310 C311 2 031 2033 CAP MYLAR FILM 0022uF 100V 10 2 C312 C313 2 038 4750 CAP P...

Page 85: ...I FILTER BREAKAWAY 0 5 2 519 0445 002 PCB MACH RFI FILTER SHIELD 1 3 519 0445 PCB MACH RFI FILTER BREAKAWAY 0 5 1 949 0192 WIRE HARNESS ME 40 SBCM 1 2 402 0000 TY RAP 40 2 402 0051 TY RAP W FLAG 15 2...

Page 86: ...BRKT BNC MOD OSC 1 2 479 6443 003 BOX MOD MODULATED OSC FX50 1 2 601 0022 WIRE AWG22 BUSS 0 166 2 611 2500 TUB HT SHK 1 4 0 083 2 693 0220 TUB TEFLON TW AWG22 NTL 0 249 2 919 0106 ASSY PCB MODLTD OSC...

Page 87: ...CM 1 3 402 0051 TY RAP W FLAG 1 3 417 0165 HSNG 5POS MOD IV S ROW 87499 9 1 3 417 0224 KEYING PLUG MOD IV 87077 AMP 1 3 417 8766 CONTACT CRIMP MOD IV 87809 1 4 3 611 1250 TUB HT SHK 1 8 2 3 621 1359 C...

Page 88: ...C23 C31 3 038 4753 CAP PYST 47UF 100V 2 C22 C30 3 040 3312 CAP MICA 33PF 350V 10 1 C35 3 040 5013 CAP MICA 50PF 500V 5 2 C37 C41 3 040 6813 CAP MICA 68PF 500V 5 1 C13 3 042 2000 CAP MICA 200PF 350V 10...

Page 89: ...0410 004 ASSY PCB REGULATOR FM 100C SBCM 1 3 030 1053 CAP MYLAR FILM 1uF 100V RAD 4 C404 C405 C406 C407 3 042 3922 CAP MICA 390PF 100V 5 3 C401 C402 C403 3 100 1231 RES 121 OHM 1 4W 1 1 R401 3 229 033...

Page 90: ...AP T B TY24M 1 1 4 DIA 4 2 420 0108 SCREW 10 32X 500 S S PHH 4 2 420 0508 SCREW 10 32X 500 S S FLH 8 2 420 8006 SCREW 8 32X 375 S S PH FLH UC 4 FOR CUSTOMER TO MOUNT OUTER SLIDE RAILS 2 420 8110 SCREW...

Page 91: ...BOM LEVEL PART NO DESCRIPTION QTY REF DES 81 2011 Broadcast Electronics 7 SCHEMATICS...

Page 92: ...dcast Electronics 4100 North 24th Street Quincy Illinois 62305 USA Phone 217 224 9600 Fax 217 224 9607 www bdcast com bdcast bdcast com Marti Electronics FM Exciter MODELS ME 40 566 017 rev D April 4...

Page 93: ...tronic or mechanical including photocopying or recording for any purpose without the express written permission of Broadcast Electronics Trademarks Broadcast Electronics and the BE logo are registered...

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