1、EIA 183 57 m 3234b00 002854b 8 m RETMA STANDARD Output Transformers for RS483 (Reafirrnafion of REC-124) Radio Broadcast Receivers 4 March 1957 Engineering Department RADIO - ELECTRONICS- TELEVISION MANUFACTURERS ASSOCIATION . EIA 183 57 M 3234600 0028547 T M %+ -* NOTICE RETMA standards are adopted
2、 in the public interest and are designed to eliminate misunder- standings between the manufacturer and the purchaser and to assist the purchaser in selecting and obtaining without delay the proper product for its particular need. Existence of such stand- ards does not in any respect preclude any mem
3、ber or non-member of RETMA from manufacturing or selling products not conforming to the standard. Any proposal of recommended standards and practices made by the Association is without any regard to whether or not their adoption may in any way involve patents on articles, materials or processes. By
4、such action, the Association does not assume any liability to any patent owner, nor does it assume any obligation whatever to parties adopting the recommended standards or practices. . ., Published by ELECTRONIC INDUSTRIES ASSOCIATION Engineering Department 2001 EYE STREET, N.W., WASHlNGTON, D. C. 2
5、0006 Copyright 1967 by Radio-Electronics-Televiuion Maniifacturrm Aesoriotion 111 riahta reserved PRICE: $1.00 Printed in U.S.A. +_ a e a EIA 183 57 3234600 0028548 L = Y RS-183 Page 1 OUTPUT TRANSFORMERS FOR RADIO BROADCAST RECEIVERS (Front Stamhrd REC-124 and Standards Proposal No. 502 fornaulated
6、 under the cognizance of the RETMA Engineerixg Receiver Components Panel) 1. PURCHASE SPECIFICATIONS SHOULD INCLUDE AT LEAST THE FOLLOWWG : 1.1 Mechanical 1.1.1 General and/or specific construction. 1.1.2 Mounting means. 1.1.3 Except as otherwise specified, a lead length of 6”. 1.2 Electrical 1.2.1
7、The impedance of each secondary load in ohms. For design purposes, this will be assumed to be a pure resistance. 1.2.2 The impedance as measured across the transformer primary when all secondaries are loaded with resistors of resistance value equal to impedances as in 1.2.1, at 400 cps and when pass
8、 ing normal dc current. 1.2.3 The normal dc current through and dc voltage on each winding with respect to a specified. datum. 1.2.4 The power to be delivered to the impedance of 1.2.2. 1.2.5 The frequency response at operating level over a specified frequency range expressed in decibels departure
9、from the 400 cycle response. 12.6 Minimum copper efficiency as defined and discussed in 2.3. . 2. PERFORMANCE 2.1 Reflected Load Impedance 2.1.1 Definition: The reflected load impedance is the imr.;.dsnce between primary terminals when the transformer is loaded at rated operating conditions. 2.1.2 M
10、ethod of Test: (a) Each secondary is loaded with a resistance numericall. equal to its specified load impedance. (b) Normal dc currents ae provided. (c) Measurements are made at 400 cycles per second. (d) Measurements are made at operating level as 1.2.4 above. 2.1.3 Limits: The reflected load imped
11、ance shall not differ from the specified value by more than * 10%. 2.2 Frequency Response 2.2.1 Definition: Frequency response at any frequency is the departure of the voltage supplied to the load at that frequency from that supplied to the load at 400 cps. 2.2.2 Method of Measurement: (a) Each seco
12、ndary is loaded with a resistance numerically equal to its specified load impedance. (b) A resistance equal to the specified reflected load impedance of the secondary is connected in series with the primary. (c) A source of variable frequency, power and voltage is connected to the circuit comprising
13、 the primary winding and the series resistor, in series. (d) Normal dc currents are provided. (e) At 400 cps and with all normal dc currents flowing, the power of the source is varied until the input power to the transformer is of the specified value. (f) The voltage across the series combination of
14、 resistor and transformer primary is then noted and held constant as the frequency of the source is varied. . f. 5 EIA 183 53 M 3234600 0028549 3 RS- 1 83 Page 2 O (g) At each frequency the secondary voltage is measured and recorded. The frequency response at any frequency is then determined by calc
15、ulating for that frequency the value of E, 20 log10 - E* Where E, is the secondary voltage at the frequency, n, and E, is the secondary voltage at 400 cycles. (Commonly the data so developed is plotted against frequency, the latter on logarithmic scale.) 2.2.3 Limits: Except as otherwise specified t
16、he voltage departure from the 400 cycle value ehall not exceed k3 db in the range from 100 to 4,000 cps. 2.3 Copper Efficiency 2.3.1 Definition: The copper efficiency is the ratio of the power supplied to the secondary load or loads to the sum of that power and power losses in the conductors compris
17、ing the secondary and primary windings, as distinguished from losses in the magnetic and other aspects of the transformer structure. 2.3.2 Method of Determination: The following terms are determined from design or otherwise by calculation : N,=Nominal primary turns. R,=Calculated nominal primary win
18、ding resistance. N,=Nominal secondary turns. R,=Calculated nominal secondary winding resistance. Copper Efficiency is then given by RL=Secondary Load resistance. ( y)2RL . x 100;F 2.3.3 Limits: Except as otherwise specified, the copper efficiency shall not be less than 75-7;. 2.4 Dielectric Tests 2.
19、4.1 Definition: Dielectric tests are overvoltage tests made to insure long life of insulation at normal operating voltages. 2.4.2 Method of Test: With the transformer at 25”C, RMS alternating voltages of substantially sinusoidal wave shapes at 60 cps and of the values given below shall be applied to
20、 the windings listed below starting with zero voltage and gradually increasing to the specified value and then decreasing gradually to zero. 2.4.3 Limits: (a) Between primary and all secondaries and core or case, 1500 volts. (b) Between secondaries which re used to couple loud speaker voice coils an
21、d core or case, 500 volts. (c) Eetween any other windings, twice the RMS working voltage. (“RMS working voltage” is identified as 0.707 times the sum of the maximum dc voltage and the peak ac voltage.) 2.5 Polarity of Windings 2.5.1 Definition: A transformer has additive polarity when the simultaneo
22、us, instantaneous voltages generated in each of the windings are in the same direction with respect to start and finish leads. 2.5.2 Method of Test: The finish of the primary winding is connected to the start of the secondary winding. An ac voltage of safe and convenient value is then applied to the primary winding. Voltages are then measpred across the windings, individually and jointly in series. 2.5.3 Limits: Transformers shall have additive polarity. The sum of the individual primary and secondary voltages shall equal the voltage measured overall. _I- r
