1、MIL-F-28874( EC) AhENDMENT 1 30 April 1984 MIL IJARY SPEC I FI CATI ON FIELD CHANGE KIT FOR VARIABLE OUTPUT POWER CAPABILITY FOR TRANSMITTER AN/URT-23( C) This amendment forms a part of Military Specification MIL-F-28874, dated 27 May 1983, and is approved for use by the Naval Electronic Systems Com
2、mand, Department of the Navy, and is available for use by all Departments and Agencies of the Department of Defense. PAGE 4 3.7.2.1, last sentence: Delete and substitute: “In the data mode, the audio input shall be the NET TEST signal at zero decibels referred to one milliwatt (dem) average power an
3、d 8.6 dEh PEP in each sideband.“ front panel shall permit he continuous adjustment of output power to desired levels between 10 mW PEP, or average, and the full output levels of TABLE I. Power control shall be provided in five switch-selected ranges of 10 dB each (50 dB total), with analog control p
4、roviding adequate resolu- tion within each range and sufficient overlap to ensure continuous control. Power output in Ehe DATA modes in the 100 W to 1000 W range shall be fixed at the maximum level specified in TABLE I for DATA modes.“. . 3.7.2.2: Delete the text and substitute: “Power output contro
5、ls located on the AM-3924( )/URT PAGE 5 TABLE I, title: Delete and substitute: “Maximum power output“. Delete last two entries in their entirety and substitute the following: “F9 (TADIL A)- 1000 W PEP O, +2 dB double side band F9j (TADIL SSB 1000 W PEP O, +2 dB f 1 dB 200 W average 100 W average Del
6、ete in its entirety. Delete the period and add: f 1 dB“ TABLE I, footnote 2“: 3.7.4b, last sentence: 3.7.5, line 5: Delete ittoggle“. 3.7.5.1: Delete the text and substitute: “for power control ranges below 100 W.“. “Forward power delivery to a 50-ohm load shall be within f1.5 dB of the indicated va
7、lue when measured at the 1000 W, 100 W, 10 W, 1.0 W, and 0.1 W points on the appropriate meter range providing upscale indication. Maximum total meter error shall not exceed 3 dB at a forward power indication of 50 mW, or 6 dB at a forward indication of 10 mW, into a 50 ohm load.“. After “3.7.5.2“,
8、add the following new paragraphs: “3.7,5.3 Final amplifier screen circuit protection. Positive protection shall be provided against damage to the AM-3924 screen bias components due to plate-to-screen arc-overs. Protection circuitry shall reset automatically when the arc extinguishes. during plate-to
9、-screen arc-overs-is permissible. A sample of the radio transmitter RF output shall be provided to a receptacle (BNC) located on the AM-3924( ) front panel. The sample port source impedance shall be nominally 50 ohms, and the sampling ratio shall be -60 d, f8 d, relative to the RF output delivered t
10、o a 50 ohm load connected to the antenna terminals.“. Blowing of primary power fuses “3.7.5.4 RF output monitor sample. 3.7.6, after the last sentence, add: IlIn addition, the transmitter with field change kit installed shall conform to the EMC requirements of MIL-T-28706. FSC 5820 1 of 2 Provided b
11、y IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-d MIL-F-28874( EC) TABLE II: Add tiie following new entries: First Requirement Test article . Production Examinatian or test paragraph paragraph inspectiqn inspect ion “Screen circuit protect ion 3.7.5.3 4.7,9 X
12、sample 3.7.5.4 4.7.10 X RF output monitor PAGE 9 After “4.7.8“, add the following new paragraphs: Il “4.7.9 Final amplifier screen circuit protection. Tests shall bse performed to verify com- pliance with 3.7.5.3. Plate-to-screen arc-overs shall be simulated in AM-3924( ) final and driver tube stage
13、s. into a 50-ohm 7oad connected to the AM-3924C front panel monitor port. Measurement shall be made with a single-tone 100 W RF output at operating frequencies of 2 MHz, 4 MHz, 8 MHz, 16 Biz, and 29.9999 MHz,“. “4.7.10 RF output monitar sample. Amplitude of the RF output monitor sample shall be measured Preparing act fv i ty: NAVY -EC (Project 5820-N788( EC) 2 of 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
