DDE7EPTX-AM2-5EAM-2.5E, 2.5 KW AM Stereo Transmitter

WARNING OPERATING HAZARDS READ THIS SHEET AND OBSERVE ALL SAFETY PRECAUTIONS ALL PERSONS WHO WORK WITH OR ARE EXPOSED TO POWER TRANSISTORS MUST TAKE PRECAUTIONS TO PROTECT THEMSELVES AGAINST POSSIBLE SERIOUS BODILY INJURY. EXERCISE EXTREME CARE AROUND SUCH PRODUCTS. UNINFORMED OR CARELESS OPERATION OF THESE DEVICES CAN RESULT IN POOR PERFORMANCE, DAMAGE TO THE DEVICE OR PROPERTY, SERIOUS BODILY INJURY, AND POSSI- BLY DEATH. DANGEROUS HAZARDS EXIST IN THE OPERATION OF POWER TRANSISTORS The operation of power 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 VOLTAGE – Normal operating voltages can be deadly. Additional information follows. B. RF RADIATION – Exposure to RF radiation may cause serious bodily injury possibly resulting in blindness or death. Cardiac pacemakers may be affected. Additional information follows. C. BERYLLIUM – OXIDE POISONING – Dust or fumes from BeO ceramics used as thermal links with power transistors are highly toxic and can cause serious injury or death. Additional information follows. D. HOT SURFACES – Surfaces of air–cooled heat sinks radiators can reach temperatures of 100 degrees centigrade and cause burns if touched. Additional information follows. E. RF BURNS – Circuit boards with RF power transistors contain high RF potentials. Do not operate an RF power module with the cover removed. HIGH VOLTAGE The transmitter operates at voltages high enough to kill through electrocution. Personnel should always break the primary circuits when access to the transmitter is required. RADIO FREQUENCY RADIATION Exposure of personnel to RF radiation should be minimized, personnel should not be permitted in the vicinity of open energized RF generating circuits, or RF transmission systems (waveguides, cables, connectors, etc.), or energized antennas. It is generally accepted that exposure to “high levels” of radiation can result in severe bodily injury includ- ing blindness. Cardiac pacemakers may be affected. The effect of prolonged exposure to “low level” RF radiation continues to be a subject of investigation and controver- sy. It is generally agreed that prolonged exposure of personnel to RF radiation should be limited to an absolute mini- mum. It is also generally agreed that exposure should be reduced in working areas where personnel heat load is above normal. A 10 mW/cm 2 per one tenth hour average level has been adopted by several U.S. Government agen- cies including the Occupational Safety and Health Administration (OSHA) as the standard protection guide for em- ployee work environments. An even stricter standard is recommended by the American National Standards Institute which recommends a 1.0 mW/cm 2 per one tenth hour average level exposure between 30 Hz and 300 MHz as the standard employee protection guide (ANSI C95.1–1982). RF energy must be contained properly by shielding and transmission lines. All input and output RF connections, such as cables, flanges and gaskets must be RF leakproof. Never operate a power tube without a properly matched RF energy absorbing load attached. Never look into or expose any part of the body to an antenna, open RF generating circuit, or RF transmission system while energized. Monitor the tube and RF system for RF radiation leakage at regu- lar intervals and after servicing. DANGER –– BERYLLIUM OXIDE CERAMICS (BeO) – AVOID BREATHING DUST OR FUMES BeO ceramic material is used as a thermal link to carry heat from a transistor to the heat sink. Do not perform any operation on any BeO ceramic which might produce dust or fumes, such as grinding, grit blasting, or acid cleaning. Beryllium oxide dust or fumes are highly toxic and breathing them can result in serious personal injury or death. BeO ceramics must be disposed of only in a manner prescribed by the device manufacturer. HOT SURFACES Heat sinks and reject loads are air–cooled or conduction–cooled. The air–cooled external surface can operate at a high temperature (up to 100°C). All hot surfaces may remain hot for an extended time after the transmitter is oper- ated to off. To prevent serious burns, take care to prevent and avoid any bodily contact with these surfaces both dur- ing and for a reasonable cooling down period after operation. TRANSMITTER WARRANTY VOID NOTICE THE PRODUCT WARRANTY WILL BE VOID IF THE TRANSMITTER IS INSTALLED AT A SITE WITH INADEQUATE LIGHTNING PROTECTION AND A DEFECTIVE TRANSMISSION LINE SYSTEM. The transmitter is covered by a two year limited product warranty from Broadcast Elec tronics. However, the transmitter must be properly installed at a site with adequate lightning protection and transmission line systems. TO ENSURE THE TRANSMIT TER WARRANTY IS VALID, the transmitter must be installed: 1) as described by the INSTALLATION procedures presented in SECTION II of this manual, 2) at a transmitter site with a lightning protection system described in TRANSMITTER SITE LIGHTNING PROTECTION SYSTEM CHECKOUT (refer to SECTION II of this manual), and 3) at a transmitter site with a transmission line system described in TRANSMISSION LINE AND ANTENNA CHECKOUT (refer to SECTION II of this manual). FAILURE TO PROPERLY INSTALL THE TRANSMITTER, PROVIDE AN ADEQUATE LIGHT NING PROTECTION SYSTEM, OR PROVIDE AN ADEQUATE TRANSMISSION LINE SYSTEM WILL VOID THE WARRANTY ON THE TRANSMITTER. If any questions develop concerning the transmitter warranty and installation site systems, con tact the Broadcast Electronics Customer Service Department. BROADCAST ELECTRONICS, INC. NOTICE TO THE EQUIPMENT USER FCC Rule 73.1590 mandates the licensee of each AM station to make measurements for spurious and harmonic emissions to show compliance with the transmission system re quirements of Section 73.44 of the Commission's Rules. It is the broadcast station's respon sibility to ensure that the audio signal applied to a Broadcast…

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FCC ID DDE7EPTX-AM2-5E EA95855 Block Diagrams All block diagrams for the AM-2.5E are located in the instruction manual. The overall block diagram for the AM-2.5E is Figure 4-3. All subassembly block diagrams can be found in the Theory of Operation sections. The instruction manual has been book marked so sections can be found easily.

November 2, 1999 Mr. Frank Coperich FCC Laboratory 7435 Oakland Mills Road PO Box 429 Columbia, MD 21045 Mr. Coperich: Enclosed are Application Forms 159 and 731, including the documentation needed for certification of the Broadcast Electronics’ Model AM-2.5E 2.5 kilowatt AM Stereo transmitter. The documentation includes Exhibits 1 - 16, covering complete data required for certification under Part 2 and Part 73 of the FCC Rules and Regulations. The instruction manual will be mailed to your attention. The AM-2.5E AM stereo transmitter has a built-in on-carrier CQUAM TM AM Stereo exciter employing digital switched modulators identical to the AM stereo exciter used in Broadcast Electronics’ Model AM- 1A stereo transmitter (FCC ID DDE7EPTX-AM-1A), which was type accepted under Part 73 of the Rules on April 14, 1997. This equipment has been tested in accordance with the requirements contained in the appropriate commission regulations. To the best of my knowledge, these tests were performed using measurement procedures consistent with the industry or commission standards and demonstrate the equipment complies with the appropriate standards. Each unit manufactured as defined in the commission’s regulations will conform to the sample tested within the variations that can be expected due to quantity production and testing on a statistical basis. I further certify that the necessary measurements were made by Broadcast Electronics, Inc. at 4100 N. 24 th Street, Quincy, Illinois. I trust that the enclosed documentation will be satisfactory to grant FCC certification of the AM-2.5E stereo transmitter. Please contact me at 217-224-9600, ext. 331, FAX at 217-224-9607, or e-mail address at [email protected] if you have any questions or need additional information. Jerry M. Westberg Senior RF Engineer RF Engineering

Exhibit 6 Photographs 2.1033 (b) (7)A sufficient number of photographs to clearly show the exterior appearance, the construction, the component placement on the chassis, and the chassis assembly. The exterior views shall show the overall appearance, the antenna used with the device (if any), the controls available to the user, and the required identification label in sufficient detail so that the name and FCC identifier can be read. In lieu of a photograph of the label, a sample label (or facsimile thereof) may be submitted together with a sketch showing where this label will be placed on the equipment. Photographs shall be 8 by 10 inches in of size A4 (21 cm x 29.7 cm) or 8 x 10 inches (20.3 cm x 25.4 cm). Smaller photographs may be submitted provided they are sharp and clear, show the necessary detail, and are mounted on paper between 8 by 10-1/2 inches and 8-1/2 by 11 inches in size A4 (21 cm x 29.7 cm) or 8.5 x 11 inch (21.6 cm x 27.9 cm) paper. A sample label or facsimile together with the sketch showing the placement of this label shall be on the same size paper. Broadcast Electronics Response Photographs clearly showing the exterior appearance and construction are given below. Rear Door Showing FCC Identifier Front/Left Rear Rear Door Open Power Supply/AC Distribution Section Combiner Power Block Mother PCB Module Power Amplifier Top View RF Amplifier PCB Bottom View Modulator PCB Top Modulator PCB Back Power Supply PCB AC Distribution Exciter/Control Unit (ECU) ECU Door Open ECU/Output Network Rear View Forward Power Meter Reflect Power Meter Exciter PCB Stereo PCB ECU Mother PCB Output Network Output Network Cover Removed Spark Gap

TABLE OF CONTENTS EXHIBITFCC RULE (S)REQUIREMENT 12.925FCC Identifier 2.926 22.947Measurement Procedure 2.1041 32.1033 (a)Application for Certification 2.1033 (b) (1-2)Name and Address, FCC Identifier 42.1033 (b) (3-5)Instruction Book 52.1033 (b) (6)Report 62.1033 (b) (7)Photographs 72.1033 (b) (8)Test Equipment 82.1033 (b) (9-12)Part 15 References 92.1046RF Power Output 73.51 73.1215 102.1047Modulation Characteristics 112.1049Occupied Bandwidth 73.44 73.128 1273.128NRSC Filter 1373.128Stereo L-R Design 142.1051Spurious Emissions 2.1057 152.1053Cabinet Radiation 2.1057 162.1055Frequency Stability FCC ID DDE7EPTX-AM2-5E APPLICANT INFORMATION FCC Certification Data For: Broadcast Electronics Model AM-2.5E AM Stereo Transmitter Prepared and Submitted By: Date: 11-2-99 Jerry M. Westberg Senior Design Engineer, RF Engineering Approved By: James R. Carpenter Vice President, RF Engineering Broadcast Electronics, Inc. P.O. Box 3606 4100 N. 24th Street Quincy, IL 62305-3606 (217)224-9600 Exhibit 1 FCC Identifier 2.925IDENTIFICATION OF EQUIPMENT. (a)Each equipment covered in an application for equipment authorization shall bear a nameplate or label listing the following: (1)FCC Identifier consisting of the two elements in the exact order specified in § 2.926. The FCC Identifier shall be preceded by the term "FCC ID" in capital letters on a single line, and shall be of a type size large enough to be legible without the aid of magnification. EXAMPLE: FCC ID XXX123, XXX-Grantee Code 123-Equipment Product Code (2)Any other statements or labeling requirements imposed by the rules governing the operation of the specific class of equipment, except that such statement(s) of compliance may appear on a separate label at the option of the applicant/grantee. (3)Equipment subject only to registration will be identified pursuant to Part 68 of this chapter. 2.926FCC IDENTIFIER. Broadcast Electronics Response Below is a picture of the FCC ID label to be riveted to the AM-2.5E Transmitter. Exhibit 2 Measurement Procedure 2.947MEASUREMENT PROCEDURE. (a)The Commission will accept data which have been measured in accordance with the following standards or measurement procedures: (Added 77-583, 10/11/77) (1)Those set forth in bulletins or reports prepared by the Commission's Office of Engineering and Technology. These will be issued as required, and specified in the particular part of the rules where applicable. (Revised 85-670, 4/14/86) (2)Those acceptable to the Commission and published by national engineering societies such as the Electronic Industries Association, the Institute of Electrical and Electronic Engineers, Inc., and the American National Standards Institute. (Added 77-583, 10/11/77) (3)Any measurement procedure acceptable to the Commission may be used to prepare data demonstrating compliance with the requirements of this chapter. (Added 77-583, 10/11/77) (b)Information submitted pursuant to paragraph (a) of this section shall completely identify the specific standard or measurement procedure used. (Added 77-583, 10/11/77) (c)In the case of equipment requiring measurement procedures not specified in the references set forth in paragraph (a)(1) and (2) of this section, the applicant shall submit a detailed description of the measurement procedures actually used. (Added 77-583, 10/11/77) (d)A listing of the test equipment used shall be submitted. (Added 77-583, 10/11/77) 2.1041 MEASUREMENT PROCEDURE. For equipment operating under parts 15 and 18, the measurement procedures are specified in the rules governing the particular device for which certification is requested. For equipment operating in the authorized radio services, measurements are required as specified in §§ 2.1046, 2.1047, 2.1049, 2.1051, 2.1053, 2.1055 and 2.1057. See also § 2.947. Broadcast Electronics Response The test procedures used for each set of measurements is attached to the exhibit containing the measured data. The test equipment and description is listed under Exhibit 7. Exhibit 3 Application for Certification 2.1033 APPLICATION FOR CERTIFICATION. (a)An application for certification shall be filed on FCC Form 731 with all questions answered. Items that do not apply shall be so noted. Read and Understood 2.1033 (b) (1)The full name and mailing address of the manufacturer of the device and the applicant for certification. Broadcast Electronics Response Broadcast Electronics, Inc. 4100 N. 24 th Quincy, IL 62301 2.1033 (b) (2)FCC Identifier. Broadcast Electronics Response FCC ID DDE7EPTX-AM2-5E Exhibit 4 Instruction Book 2.1033 (b) (3)A copy of the installation and operating instructions to be furnished the user. A draft copy of the instructions may be submitted if the actual document is not available. The actual document shall be furnished to the FCC when it becomes available. Broadcast Electronics Response A copy of the Instruction Book has been sent to the FCC for their review. See Part 1, Section 2 (Installation) of the Instruction Book for the installation instruction and Part 1, Section 3 (Operation) for the Operation instructions. (4)A brief description of the circuit functions of the device along with a statement describing how the device operates. This statement should contain a description of the ground system and antenna, if any, used with the device. Broadcast Electronics Response A description of the circuit functions of the AM-2.5E along with how the circuits function can be found in Part 1, Section 4 (Theory of Operation) of the Instruction Book. (5)A block diagram showing the frequency of all oscillators in the device. The signal path and frequency shall be indicated at each block. The tuning range(s) and intermediate frequency(ies) shall be indicated at each block. A schematic diagram also is required for intentional radiators. Broadcast Electronics Response The overall block diagram for the AM-2.5E is shown on Figure 4-1 found in Part 1, Section 4 of the Instruction Book. All block diagrams of the subassemblies in the …

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FCC ID DDE7EPTX-AM2-5E EA95855 Schematic Diagrams All schematic diagrams for the AM-2.5E are located in the instruction manual in Section VII Drawings. The instruction manual has been book marked so sections can be found easily.

Exhibit 7 Test Equipment 2.1033 (b) (8)If the equipment for which certification is being sought must be tested with peripheral or accessory devices connected or installed, a brief description of those peripherals or accessories. The peripheral or accessory devices shall be unmodified, commercially available equipment. Broadcast Electronics Response TEST EQUIPMENT LIST 1.Audio Precision System One, S/N 32497. 2.Bird 10 kW water load. 3.Blue M Electric Model CO-250CX Environmental Chamber, S/N CB-219. 4.Broadcast Electronics Model AS-10 AM Stereo Modulation Monitor. 5.Broadcast Electronics Capacitive RF Voltage Pick up, Test Fixture. 6.Circuit Research Labs (CRL) Amigo Audio Processor, S/N GG1061. 7.Compaq Portable II Computer. 8.Delta Electronics Model TCA-5/10EXR RF Ammeter, S/N 6246. With Model TCT-4 Transformer, S/N 6246. 9.Delta Electronics Model SNG-1 Stereo Noise Generator, S/N 0092. 10.Epson Model EX-800 Line Printer. 11.Fluke Model 75 Digital Multimeter. 12.Fluke Model 77 Digital Multimeter. 13.Fluke Model 80T-150U Temperature Probe. 14.Hewlett-Packard Model 3585B Spectrum Analyzer, S/N 2824A00461. 15.Hewlett-Packard Model 8591 EM Spectrum Analyzer, S/N 3520A00191. 16.Hewlett-Packard Model 4193A Vector Impedance Meter, S/N 2830J02440. 17.Hewlett-Packard Model 5315B Universal Counter, S/N 2510A03455. 18.Hewlett-Packard Model 7470A Plotter, S/N 2308A 74847. 19.Pioneer Model PD-101 Compact Disc Player, S/N MC3611404 AS. 20.Tektronix Model 2445 Oscilloscope, S/N B021942. 21.Texscan FP-50 3 dB Attenuator Pad. 22.Texscan FP-50 10 dB Attenuator Pad. 23.Texscan FP-50 20 dB Attenuator Pad. 24.Yokogawa Electric Works Type 2011 Class 0.5 Ammeter, S/N 77AA0014. 25.Emco Model 6512 Passive Loop Antenna Exhibit 8 Part 15 References 2.1033 (b) (9)For equipment subject to the provision of Part 15 of this chapter, the application shall indicate if the equipment is being authorized pursuant to the transition provisions in § 15.37 of this chapter. (10)Applications for the certification of direct sequence spread spectrum transmitters under part 15 shall be accompanied by an exhibit demonstrating compliance with the processing gain provisions of § 15.247(e) of this chapter. Applications for the certification of frequency hopping transmitters under part 15 shall be accompanied by an exhibit describing compliance of the associated receiver or receivers with § 15.247(a)(1) of this chapter. (Added 98-58, 10/5/98) (11)Applications for the certification of scanning receivers shall include a statement describing the methods used to comply with the design requirements of all parts of § 15.121(a) of this chapter. or the marketing requirements of § 15.121(b) of this chapter. The application must specifically include a statement assessing the vulnerability of the equipment to possible modification and describing the design features that prevent the modification of the equipment by the user to receive transmissions from the Cellular Radiotelephone Service. The application must also demonstrate compliance with the signal rejection requirement of § 15.121 of this chapter, including details on the measurement procedures used to demonstrate compliance. (12)Applications for certification of transmitters operating within the 59.0—64.0 GHz band under part 15 of this chapter shall also be accompanied by an exhibit demonstrating compliance with the provisions of § 15.255 (g) and (i) of this chapter. (Added 98-58, 10/5/98) Broadcast Electronics Response Not Applicable. Exhibit 9 RF Power Output 2.1046 MEASUREMENTS REQUIRED: RF POWER OUTPUT. (a)For transmitters other than single sideband, independent sideband and controlled carrier radiotelephone, power output shall be measured at the RF output terminals when the transmitter is adjusted in accordance with the tune-up procedure to give the values of current and voltage on the circuit elements specified in § 2.1033(c)(8). The electrical characteristics of the radio frequency load attached to the output terminals when this test is made shall be stated. (c)For measurements conducted pursuant to paragraphs (a) and (b) of this section, all calculations and methods used by the applicant for determining carrier power or peak envelope power, as appropriate, on the basis of measured power in the radio frequency load attached to the transmitter output terminals shall be shown. Under the test conditions specified, no components of the emission spectrum shall exceed the limits specified in the applicable rule parts as necessary for meeting occupied bandwidth or emission limitations. (Added 74-113, 3/25/74) 73.51DETERMINING OPERATING POWER. (a)Except in those circumstances described in paragraph (d) of this section, the operating power shall be determined by the direct method. The direct method consists of either: (Revised 84-628- 12/12/84) (1)using a suitable instrument for determining the antenna's input power directly from the RF voltage, RF current, and phase angle; or (Added 84-628, 12/12/84) (2)calculating the product of the licensed antenna or common point resistance at the operating frequency (see § 73.54), and the square of the indicated unmodulated antenna current at that frequency, measured at the point where the resistance has been determined. (Added 84-628, 12/12/84) (d)When it is not possible or appropriate to use the direct method of power determination due to technical reasons, the indirect method of determining operating power (see paragraphs (e) and (f) of this section) may be used on a temporary basis. A notation must be made in the station log indicating the dates of commencement and termination of measurement using the indirect method of power determination. (Added 84-628, 12/21/84) (e)The antenna input power is determined indirectly by applying an appropriate factor to the input power to the last radio-frequency power amplifier stage of the transmitter, using the following formula: (Revised 79-369, 7/2/79) Antenna input power = Ep x Ip x F Where: Ep=DC input voltage …

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Exhibit 12 NRSC Filter 73.128 (c)Effective on December 20, 1994, stereophonic transmissions shall conform to the following additional modulation characteristics: (1)The audio response of the main (L+R) channel shall conform to the requirements of the ANSI/EIA-549-1988, NRSC-1 AM Preemphasis/Deemphasis and Broadcast Transmission Bandwidth Specifications (NRSC-1). (2)The left and right channel audio signals shall conform to frequency response limitations dictated by ANSI/EIA-549-1988. (5)Maximum angular modulation, which occurs on negative peaks of the left or right channel with no signal present on the opposite channel (L(t)=-0.75, R(t)=0, or R(t)=-0.75, L(t)=0) shall not exceed 1.25 radians. Broadcast Electronics Response RESPONSE: The filter needed to insure the transmitter complies with the Transmission Bandwidth Specifications (NRSC-1) and the limitations dictated by ANSI/EIA-549-1988 will be located in the audio processor which is attached to the transmitter. Each Instruction Manual will have a note to the equipment user as shown below. NOTICE TO THE EQUIPMENT USER FCC Rule 73.1590 mandates the licensee of each AM station to make measurements for spurious and harmonic emissions to show compliance with the transmission system requirements of Section 73.44 of the Commission's Rules. It is the broadcast station's responsibility to ensure that the audio signal input to the Broadcast Electronics' model AM- 500A, AM-1A, AM-500A, AM-10A, AM-2.5E and AM-5E stereo transmitters conform to the audio standard NRSC-1 (published as ANSI/EIA-549-1988). This is a mandatory requirement to ensure that the equipment complies to Section 73.44 and Section 73.128(c) of the Commission's Rules. Exhibit 13 Stereo L-R Design 73.128 (3)The stereophonic difference (L-R) information shall be transmitted by varying the phase of the carrier in accordance with the following relationship: Where: L(t) = audio signal left channel, R(t) = audio signal right channel, m = modulation factor, and mpeak(L(t) + R(t)) = 1 for 100% amplitude modulation, mpeak(L(t) - R(t)) = 1 for 100% phase modulation. (4)The carrier phase shall advance in a positive direction when a left channel signal causes the transmitter envelope to be modulated in a positive direction. The carrier phase shall likewise retard (negative phase change) when a right channel signal causes the transmitter envelope to be modulated in a positive direction. The phase modulation shall be symmetrical for the condition of difference (L-R) channel information sent without the presence of envelope modulation. (6)A peak phase modulation of +/-0.785 radians under the condition of difference (L-R) channel modulation and the absence of envelope (L+R) modulation and pilot signal shall represent 100% modulation of the difference channel. (7)The composite signal shall contain a pilot tone for indication of the presence of stereophonic information. The pilot tone shall consist of a 25 Hz tone, with 3% or less total harmonic distortion and a frequency tolerance of +/-0.1 H2, which modulates the carrier phase +/-0.05 radians peak, corresponding to 5% L-R modulation when no other modulation is present. The injection level shall be 5%, with a tolerance of +1, -1%. (8)The composite signal shall be described by the following expression: A = the unmodulated carrier voltage m = the modulation index Csn = the magnitude of the nth term of the sum signal Cdn = the magnitude of the nth term of the difference signal wsn = the nth order angular velocity of the sum signal wdn = the nth order angular velocity of the difference signal wc = the angular velocity of the carrier fsn = the angle of the nth order term = tan-1 ( Bsn / Asn ) fdn = the angle of the nth order term = tan-1 ( Bsn / Asn ) Asn and Bsn are the nth sine and cosine coefficients of Csn Adn and Bdn are the nth sine and cosine coefficients of Cdn Broadcast Electronics Response Complies. See simplified schematic Figure 4-5 in the Instruction manual. The Theory of Operation 4-92 through 4-101 has been copied below. 4-92. EXCITER CIRCUIT BOARD. Audio for application to the AM-2.5E/AM-5E transmitter is applied to the exciter circuit board (refer to Figure 4-4). The exciter circuit board is designed to: 1) process left/right channel or monaural audio to generate a Pulse-Width-Modulated (PWM) signal at 122 kHz to 135 kHz and 2) generate an RF signal using a frequency synthesizer, a phase modulator for IPM correction, and an RF driver network. 4-93.Left channel audio is applied to an RFI filter and a defeatable 10 Hz high-pass filter. The 10 Hz high-pass filter is provided to remove low frequency residual products from specific audio processing units. Balanced-to-unbalanced signal conversion is provided by an instrumentation amplifier. The output of the instrumentation amplifier is applied to a defeatable high frequency boost circuit. The high frequency boost circuit is provided to increase high frequency response to compensate for a Bessel filter in the PWM modulator. The output of the high frequency boost circuit is applied to an active PWM filter/equalizer and a mode switching circuit. The output of the PWM filter is routed for application to the stereo circuit board. 4-94.The mode switching circuit is designed to select the left or right channel for mono left or mono right operation. A summing amplifier is provided as a mono support circuit to increase the gain of the circuit 6 dB during mono operations. The output of the summing amplifier is applied to a 24 uS delay and limiter circuit. The delay circuit is provided for stereo equalization. The negative limiter is provided to limit negative modulation from 90% to 100%. 4-95.The output of the 24 uS delay and negative limiter is applied to: 1) a PWM circuit and 2) an IPM comparator and corrector circuit. The PWM circuit is designed to output a square wave signal in which the duty cycle changes in response to the applied audio level. The output of the PWM circuit is applied to a PWM d…

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Exhibit 11 Occupied Bandwidth 2.1049 MEASUREMENTS REQUIRED: OCCUPIED BANDWIDTH. The occupied bandwidth, that is the frequency bandwidth such that, below its lower and above its upper frequency limits, the mean powers radiated are each equal to 0.5 percent of the total mean power radiated by a given emission shall be maintained under the following conditions as applicable: (Added 74- 113, 3/25/74) 73.44AM TRANSMISSION SYSTEM EMISSION LIMITATIONS. (a)The emissions of stations in the AM service shall be attenuated in accordance with the requirements specified in paragraph (b) of this section. Emissions shall be measured using a properly operated and suitable swept-frequency RF spectrum analyzer using a peak hold duration of 10 minutes, no video filtering, and a 300 Hz resolution bandwidth, except that a wider resolution bandwidth may be employed above 11.5 kHz to detect transient emissions. Alternatively, other specialized receivers or monitors with appropriate characteristics may be used to determine compliance with the provisions of this section, provided that any disputes over measurement accuracy are resolved in favor of measurements obtained by using a calibrated spectrum analyzer adjusted as set forth above. (Revised 89-118, 6/30/90) (b)Emissions 10.2 kHz to 20 kHz removed from the carrier must be attenuated at least 25 dB below the unmodulated carrier level, emissions 20 kHz to 30 kHz removed from the carrier must be attenuated at least 35 dB below the unmodulated carrier level, emissions 30 kHz to 60 kHz removed from the carrier must be attenuated at least [5 + 1 dB/kHz] below the unmodulated carrier level, and emissions between 60 kHz and 75 kHz of the carrier frequency must be attenuated at least 65 dB below the unmodulated carrier level. Emissions removed by more than 75 kHz must be attenuated at least 43 + 10 Log (Power in watts) or 80 dB below the unmodulated carrier level, whichever is the less…

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