Carrier 398A Operator's Manual

TM 11-5820-398-35DEPARTMENT OF THE ARMY TECHNICAL MANUALFIELD AND DEPOTMAINTENANCE MANUALRADIO SET AN/PRC-25This copy is a reprint which includes curr

j. Set the rf output of the AN/URM-48for 53.00 mc, modulated ±10 kc by a 1,000-cps tone.k. Set the BAND switch of the receiver-transmitter at 53-75, a

CHAPTER 4FOURTH ECHELON MAINTENANCESection I. FOURTH ECHELON46. Scope of Fourth Echelon RepairsFourth echelon maintenance includesthose functions allo

secure the selector mechanismhousing assembly to the chassis.(6) Replace tuning capacitors C1 andC2 and secure them with fourscrews.Note: Do not tigh

Figure 36. Receiver-Transmitter, Radio RT-505/PRC-25, top view, audio and controlchassis open.Figure 37. Receiver-Transmitter, Radio RT-505/PRC-25, fr

and secure it with the three audioand control chassiscaptivescrews.48. Removal and Replacement of SelectorMechanism(fig. 37, 38, and 40)a. Removal.(1)

Figure 38. Front panel, rear view.Figure 39. Tuning capacitor assembly.65

Figure 40. Tuning knob assembly.Section II. FOURTH ECHELON ALIGNMENT49. Generala. Scope of Fourth Eohelon AlignmentProcedures. Fourth echelon alignme

rotation curve by turning C1 counterclockwise (fromshaft end) and noting that the 520 indicates a de-crease in capacity. Reset to 68 microfarads (uuf

Figure 41.(2)(3)nections or test indications thatmay differ from those given inthe test procedures.Unless otherwise specified, alltests are to be perf

55.69

Figure 42.70

56.71

Figure 43.72

57.73

Figure 44.74

58.75

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Figure 45.78

59.79

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Figure 46.

60.83

Figure 47.84

61.85

Figure 48.86

62.figure 4887

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Figure 49.90

63.figure 4991

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Figure 50.94

64.figure 5095

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Figure 51.98

65.figure 5199

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Figure 52.102

66.figure 52103

67. Summary of Test DataPersonnel may find it convenient toarrange the checklist in a manner similarto that shown below.TestTestPerformance standardda

CHAPTER 5FIFTH ECHELON MAINTENANCE68. Scope of Fifth Echelon MaintenanceThe functions allocated to fifth echelonmaintenance level include troubleshoot

(2) Connect the handset to eitherAUDIO connector.b. Performance Test.(1) Press the handset push-to-talkswitch.(2) Set the ME-26 B/U to the 300-volt,dc

Figure 53. Module A1 parts location.108

(12)(13)(14)(15)(16)(17)procedure given in (9) above shouldbe 1,100 kc.Change the receiver-transmitterBAND switch to 53-75.Adjust the AN/URM-48 freque

Figure 54. Module A2 parts location.diagrams and to figures 55 and 56 for test(2)points and parts location.a.Preparation.(1) Prepare the following equ

noted in (3) above. Record the fre-(b) Dc voltage chart.(9)(10)(11)(12)(13)quency.Increase the AN/URM-48 fre-quency until the output level indi-cated

(11)(12)indication cannot be increased bytuning.Remove the shorting jumper frompins E and H of J9.Replace A5.74. Isolating Trouble in Module AS(fig. 3

(9)(10)(11)(12)Figure 56. ModuleIncrease the AN/URM-48 fre-quency until the level indicated bythe 411A is again at the levelnoted in (5) above. Record

receiver-transmitter front panel controlsas follows:(1) Turn the BAND switch to 30-52.(2) Turn the tuning knobs to 30.00 mc.(3) Turn the function swit

(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)frequency difference is the 3-dbbandwidth, which should be 1,200kc.Adjust the AN/URM-48 frequencyto 52

(9)(lo)(11)(12)(13)(14)(15)(16)(17)(18)Repeat the procedures given in (1)through (8) above until the 411Aindication cannot be increased bytuning.Set t

(2)(3)(4)(5)(6)(7)(8)(9)(lo)(11)(12)(13)(14)(15)(16)Connect the 411A across the AN/URM-48 output. Press the push-to-talk switch. Adjust the AN/URM-48f

(2) After the replacement of a faultypart, perform the alignment proce-dures given in d and e below, andrepeat the procedures in a and babove.d. Pr

Figure 59. Module(5)(6)(7)(8)(9)(lo)(11)(12)tain a O-db indication on the 411A.Increase the AN/URM-48 fre-quency until the 411A indicates a3-db decrea

(22) If the gain and bandwidth do notmeet the standards of the proce-dure, proceed to c below.c. Faulty Parts Isolation.(1) Remove module A9. Connect

Figure 60. Module A8, parts location.Connect the ME-26B/U to A9J3.Connect the 411A to A9J4.Set the receiver-transmitter frontpanel controls as follows

(9)(10)(11)(12)(13)Disconnect the 411A from J20. Re-place A14. Connect the 411A toA9J4.Set the receiver-transmitterBAND switch to 53-75.While rotating

(15)(16)(17)(18)(19)(20)(21)50 kc, as indicated by the AN/USM-26.If the frequency difference givenin (11) above is greater than thatgiven in (7) above

(5)(6)(7)(8)(9)(10)Figure 61. Module A9, parts location.47.050; the 411A should indicate0.2 volt.Set the tuning knobs for 30.30 mc.The AN/USM-26 shoul

(7)(8)(9)(10)A10J3 ana reconnect the AN/USM-26. The AN/USM-26 should indi-cate 5.6000 mc.Connect the H-138/U to an AUDIOconnector and press the push-t

Figure 62. Module A10, parts location.(3) Turn the receiver-transmitterfunction switch to ON.b. Dc output Level Test.(1)(2)(3)(4)Connect the AN/URM-48

(2)(3)(4)(5)(6)Adjust transformer T1 for a maxi-mum dc indication on the ME-26B/U.Set the output of the AN/URM-48to 5.20 mc.Adjust transformer T2 for

(a) Signal voltage chart.Point of measurementVolts (rma )~----------------------------(b) Dc voltage chart.0.0080.00.800.10Point of measurementVoltag

procedure given in (8) above dif-fers from that indicated in (5) aboveby more than 2 db, proceed to thealignment procedures in c below.(10) If the ind

83. Isolating Trouble in Module A14(fig. 17 and 66)a. Preparation.(1) Prepare the following equipment:(a) Signal Generator AN/URM-48.(b) Frequency Met

(9)through (7) above and adjust T2 un-til the indications given in (4) and(6) above are equal. Perform thisstep as required.Replace module A9.c. Fault

Figure 67, Module A15, parts location.(receptacle for A16) and insert A16into the module extender.(2) Prepare Multimeter ME-26B/U.(3) Set the front pa

(b)(c)(d)(e)(f)(2)(3)(4)(5)(6)(7)(8)Rf Millivoltmeter 411A.Oscilloscope AN/USM-50A.R. F. Signal Generator AN/URM-25F.Frequency Meter AN/USM-26.Module

Figure 69. Module A17, parts locationb. Gain Test.(1) Connect the AN/URM-25F be-(2)(3)(4)(5)(6)tween pin F of A18J1 and ground.Connect the 411A and th

(a) Signal voltage chart.Point of measurementVolta (rms)Q1 base -------------------—---Ql emitter ---— ----------------Ql collector ------------------

(15)(16)(17)(18)(19)A20J2 and connect the AN/USM-26to that point.Press the push-to-talk switch.The AN/USM-26 should indicate11.5485 mc ±300 cps.Releas

CHANGENo. 2Changes in force C 1 and C 2TM 11-5820-398-35C2HEADQUARTERSDEPARTMENT OF THE ARMYWASHINGTON , D. C., 22 April 1965Field and Depot Mainte

Figure 71. Module A19, parts location.Place the alignment cover (fig. 28)on A20.(3) Insert themoduleextender into J16(receptacle for A20). Insert A20i

(b) DC voltage chart.Point of measurementQ1 tW3~ -------------------Q1 emitter -------—--— -------Q1 collector ---------------—--CR1-C4 junction----

(3)(4)(5)(6)(7)(8)(9)(lo)(11)(12)(13)(14)(15)(16)(17)(18)Adjust the output of the AN/URM-48 until the voltage indicated on the411A is 100 millivolts.

Point of mewurementMillivolta (rms)Q5 colleotoro ----------------160Q5 baeeo -------------------49Q6collecto@ -------------------1.65Q6 ksecvolts----

(4)given above for 300 cps, 2 kc, and3 kc. Normal test results for eachsetting is 3.5 percent. Normal out-put signal level for each setting is1.4 volt

c. Faulty Part Isolation.(1) Measure the voltages at the pointslisted in the charts in (a) and (b)below. Compare them with the nor-mal signal and dc

(8)(9)(10)(11)Increase the TS-382F/U frequencyto 160 cps. The ME-26B/U indica-tion should remain zero.Increase the TS-382F/U frequencyto 170 cps. The

(3)Figure 76. Module A24, parts location.Measure the voltages at the pointslisted in the charts in (a) and (b)below. Compare them with the nor-mal si

Figure 77. Module A25, parts location.d. Remove retaining ring (12) fromshaftassembly (30) and remove shaft assembly(30), with thrust washer (31) and

o. Remove spring (83) and sleeve (84)from mask assembly (53).p. Remove retaining ring (79) that se-cures arm assembly (78) to shaft assem-bly (57). Re

figure 10 figure 10.1 Page 20.TM5820-398-35-C2-1Figure 10.1.2

assembly (63) on shaft assembly (75). Alignthe holes; insert and secure taper pin (62)and setscrew (64).f. Place thrust washer (77) and spurgear (73)

Figure 78. Selector mechanisrn, exploded view.148

1 Retaining ring2 Sleeve3 Bushing4 Arm5 Pin6 Spring7 Taper pin8 Setscrew9 Screw10 Lockwasher11 Plate12 Retaining ring13 Taper pin14 stop15 Setsc

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1 Coupling assembly2 Screw3 Support bearing assembly4 Hexagonal nut5 Washer6 Board assembly7 Header-shield assembly8 Cover910111213141516LockwasherPan

COLOR CODE MARKING FOR MILITARY STANDARD RESISTORSCOMPOSITION-TYPE RESISTORSWIREWOUND-TYPE RESISTORSBAND A—Equal Width BandBAND A—Double Width Signifi

Page 43, paragraph 36a, (page 8 of C 1) chart.Delete the last line and substitute: RF Millivolt-meter, Hewlett-Packard Model HP411A.Page 56, figur

161Figure 85.

Figure 86.163

Figure 87.165

APPENDIXREFERENCESTA 11-17TA 11-100 (11-17)TM 11-1257TM 11-5057TM 11-5097TM 11-5129TM 11-5133TM 11-5551ETM 11-5820-398-10TM 1l-5820-398-20TM 11-5820-3

INDEXParagraphAdditional equipment required:Fourth echelon testing procedures---Third echelon maintenance ---------Alignment:Power amplifier tank modu

ParagraphA18---------------------------A19---------------------------A20---------------------------A21---------------------------A22------------------

ParagraphPublications, index -------------------Quarter-wave network, module A19,theory----------------------------Reassembly, selector mechanism ----

Paragraph PageParagraph PageA2------------------------------A3 A4 A5------------------------------A6------------------------------A7 A8 --------------

By Order of Secretary of the Army:Official:J. C. LAMBERT,Major General, United States Army,The Adjutant General.DistributionActive Army:174DASA (6)USA

WARNINGDANGEROUS VOLTAGES EXIST IN THIS EQUIPMENTWhen Receiver-Transmitter, Radio RT-505/PRC-25is in a transmit condition, 45 volts dc and 125 voltsdc

Figure 61.1.Page 124, figure 61.Add figure 61.1 after figure 61:4TAGO 8344-A

PIN: 018817-000

This fine document...Was brought to you by me: Liberated Manuals -- free army and government manualsWhy do I do it? I am tired of sleazy CD-ROM sell

Page 151. Add chapter 6 after figure 79:CHAPTER 6DEPOT INSPECTION STANDARDS98. Applicability of Depot Inspection Stand-(2)ardsThe tests outlined in th

EquipmentSwitch, tig~e, singl&pole, singl~throw -------------------------------------------------Barrier terminal biock, Cinch Jones type No. 2-17

Eguipmenf,d?rd dock No. %%2Capacitor, O.05pf +10To,4M vdc-----------------------------------------------------Wire, stranded AWGNo. l8----------------

Figure 79.2. Test cables No. 4, No.5, and No.6.8TAGO 8344-A

Figure 79.3. Test cables No. 7, No. 8, and No. 9.TACO 8344-A9

Figure 79.4. Receiver dummy antenna, schematicand wiring diagrame.10TAGO 8344-A

Figure 79.5.11TACO 8344-A

Figure 79.6. Test assembly, schematic/wiring diagram.12TAGO 8344A

101. General Test RequirementsMost of the tests will he performed under theconditions listed below and illustrated in figure 79.7(for the receiver sys

Figure 79.7.14TAGO 8344-A

103. Transmitter Test Setup(fig. 79.8)a. Plug the test assembly connector into POWERconnector J3 on the front panel of the RT–505/PRC-25.b. Connect a

Figure 79.8.16TAGO 8344-A

(7)(8)723A/U (used as a vacuum-tube voltmeter)should be not greater than 0.02 volt.Reestablish the standard receiver testconditions; use the HP-200AB

the space between module Al0 and thebrass wheel-like part of the coupling.(3) Adjust RT-505/PRC-25 to a frequency50-kc higher than its current setting

(9)(l0)Repeat the procedures given in (7) and(8) above except increase the RF output70 db to determine the 70-db-downpoints. The 70-db-down points sho

(3)(4)(5)(6)(7)Record the RF and audiofrequenciesbeing used and the deviation indicated onthe ME-57/U.Set the test assembly TRANSMITTERCARRIER switch

Short antenna loadingLoad characteristics————-—————MinimumTest frequency (mc)ResistancevoltageCapacitancee (rms)(ohms)——————(uff)—— —— —————30.00-----

106. Miscellaneous System Tests and In-spection, Radio Set AN/PRC-25a. Tests.(1)(2)(3)(4)(5)(6)Perform the miscellaneous system testswith the equipmen

By Order of the Secretary of the Army:official:J. C. LAMBERT,Major General, United States Amy,The Adjutant General.Distribution:Active Army:USASA (2)C

2Figure 5.1.TM 5820-396-35-CI-9

TM 11-5820-398-35Technical ManualNo. 11-5820-398-35CHAPTERC HAPTERSectionCHAPTERSectionCHAPTERSectionCHAPTERA PPENDIX1.2.I.II.3.I.II.III.IV.4.I.II.III

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CHAPTER 1INTRODUCTION1. Scopea. This manual covers field and depotmaintenance for Radio Set AN/PRC-25. Itincludes instructions appropriate to third,fo

CHAPTER 2THEORYSection I. BLOCK3. Receiving Signal Path(fig. 82)Receiver-Transmitter, Radio RT-505/PRC-25 is tunable in 50-kilocycle (kc)increments ov

f. The receiver audio amplifier output,including the 150-cps tone, is applied tothe squelch input amplifier. The squelchinput amplifier with the emitt

those used for transmission, unless other-wise indicated, by subtraction of 50 kcfrom the given frequency.a. The vfo output frequency ranges from41.50

also has an input from the 50-kc intervaloscillator.g. The- 50-kc interval oscillator gen-erates one of three frequencies: 5.55 mc,5.60 mc, or 5.65 mc

(2)High band. Transformer T3, fixedcapacitor C11, trimmer capacitorC9, and tuning capacitor C2C makeup the tuned circuit. Switch S1-Dshorts the low-ba

9Figure 1.

Figure 2.10

(2)the tuned circuit consisting of ca-pacitor C9 and the primary windingof transformer T1.The combination of resistors R2and R3, R7 and R8, and R11 an

tively. Resistors R17 and R21 arecollector load resistors for Q4 andQ5, respectively.c. Receiver Discriminator Driver Q6.The receiver discriminator dr

Figure 4. Receiver audio amplifierlower Q2 have a common emitter resistor,R6. Transistor Q2 operates near satura-tion. Audio input signals from the au

cycles of the 150-cps signal will causethe amplifier-detector to conduct. The out-put developed across collector load resis-tor R18 is a negative-goin

coupling capacitor C7 to the base of outputlimiter Q3. The output limiter signal isdeveloped across collector load resistorsR17 and R18. The audio out

13. Tone Generator Module A23(fig. 7)The tone oscillator functions only duringtransmission. The 150-cps output tone isapplied to the speech amplifier

network contributes a stability f actor about40 times greater than that of a free-run-ning oscillator.a. Sidestep Oscillator Module.(1)(2)(3)The audio

Figure 8. Sidestep oscillator module A20, schematic diagram.isolation, and proper match for the vfosignal applied to the fss. An output fromthe vfo is

Figure 9. Quarter-wave network module A19, schematic diagram.emitter. Inductor L3 and capacitorC13 form a filter network to pre-vent rf leakage into t

Figure 10.20

Figure 11.21

decreasing the total capacitance. The rfinput to module A8 can be measured attest jack J2.d. Inductor L2 and capacitors C6 andC7 (in the main frame (f

c. Capacitors C2 and C3 and inductorL1 prevent rf variations from reaching the-45-volt dc supply. The combination ofresistors R2 and R3 provides fixed

Figure 13. Transmitter ipa module A6, schematic diagram.the -45-volt supply. A pi-type filter con-sisting of capacitors C2 and C5 and induc-tor L2 pre

Figure 14. Power amplifier A29, schematic diagram.L1 (low band) or capacitor C4 (high band)through switch SIB, through pin 3 of 2AJ1and pin 9 of J7 to

Figure 15. Power amplifier tank module A2, schematic diagram.controls tune inductorswhich are in series withc. The tuningL1, L2, and L3,capacitors C2

Figure 16. Antenna loading network A28, schematic diagram,Figure 17. First mixer module A14, schematic diagram.27

ing of diode CR3, capacitor C5, and re-sistor R8, to the center tap of the primaryof transformer T2. It is terminated in atuned network consisting of

(2)Figure 18. 1-mc spectrum generator moduleC10 to the selected crystal ((2) be-low), and the contacts of S1A to theemitter of Q2; this action com-ple

5Figure 7.1. TM5820-398-35-CI-4

(4)and A10J1 and current-limiting re-sistor R7 to the anode of CM. Thispositive voltage forward biasesCR2; the diode conducts heavily andallows the re

Figure 19.31

Figure 20. 53-Mc filter module A 13, sthematic diagramthe filter properly and minimize varia-tions due to the varying impedances oftransistors. The rf

Figure 21. Second mixer moduleA12, schematic diagram.output termination and minimizesvariations due to discriminatorloading. The combination of resis-

Figure 22. Speech amplifier limiter module A18, schematic diagram.transformer T1. Resistors R1 and R2 forma voltage divider which provides the fixed-b

(4)(5)Figure 23. Phase comparator module A17, schematic diagram.since E1 and E2 voltages are ex-actly 180° out-of -phase.If the vfo frequency increase

apc voltage in its output circuit. The twoinput signals are the fss if. signal from thefss if. amplifier module A18 (para 27) anda dc voltage from pha

Figure 24. Fss discriminatormaintains a constant voltage drop. When theoutput voltage increases due to a decreasein load or an increase in the input v

38(2)Figure 25. Voltage regulator module A16, schematic diagram.condition induces a voltage in thefeedback winding of transformerT1. The voltzage is a

used in conjunction with Test Set, Elec-tronic Plug-in Circuit AN/GRM-55 to iso-late a faulty module at the organizationallevel. If usedproperly, howe

the output of oscillator Q1 (in A10) to bechecked. A typical rf signal level at thistest point is 0.2 volt. Test point J3 permitsthe output of oscilla

the 0A-3633/GRC. The power distributionwhen a BA-386/PRC-25 is used is similarexcept that a shorting cap is installed onJ3 and the BA-386/PRC-25 is co

CHAPTER 3THIRD ECHELON MAINTENANCESection I. GENERAL TROUBLESHOOTING TECHNIQUESWarning: Be extremely careful when servicing the RT-505/PRC-25. During

PRC-25. The charts also list the associ-ated technical manuals for the equipment.a. Test Equipment.‘hat equipmentMultimeter ME-26 B/U ---R;3tV#meter

Figure 28. Typical alignment cover formodule A20.Section II. THIRD ECHELON TROUBLESHOOTINGCaution: Do not attempt removal or replacement of parts bef

(d) Connect Handset H-138/U to oneof the receiver-transmitter AU-DIO connectors.(e) Set the receiver-transmittercontrols as follows:ControlPosition o

Item345646IndicationReceived signals are not heard,but a rushing noise is heard fnthe H-138/U when the functionswitch is at ON and the longantenna is

Item78Indicationeither band when the hmctionswitch is at ON. Transmitoperation is normal.A rush?noise is heard in theH-138 U when the function switcis

Item9101112indicationin the H-138/U with. the iimctionswitch at SQUELCH.b output ia heard in the H-138/Uwhen the function switch ia atSQUELCH in eith

Item131415Mm12IndicationReceives signal on the wrongchannel. Transmit operationis normal.High-frequency noise in the audiooutput.Tuning knobs do not f

7TM5820-398-35-CI-2Figure 22.1.

Item3450Indicationo rf Power output indicated on theAN/URM-43A on one band. Re-ceiver operation ia normal onboth bands.o rf power output indicated on

Item56789101112Indication?ranamits and receives signals onwrong channel on either band.?ranamits signal on wrong channelon either band.” Receiver

Item13141516Indicationis at SQUELCH. Receiver oper-ation is normal.Transmits a modulated carrierthat cannot be received when anRT-505/PRC-25 at the re

Figure 29. Transmitter power amplifier test points and parts location.Section III. THIRD ECHELON REPAIRS40. Scope of Third Echelon Repairsand all othe

41. Removal and Replacement of Audioand Control Chassis A27(fig. 32)a. Removal.(1)(2)(3)(4)(5)(6)(7)(8)(9)Remove modules A21 through A25as described i

55Figure 30. Receiver-Transmitter, Radio RT-505/PRC-25, bottom view.

Figure 31. Receiver-Transmitter, Radio RT-505/PRC-25, bottom view, modules removed.56

Figure 32. Receiver-Transmitter, Radio RT-505/PRC-25, top view.57

TM 5820-398-35-31Figure 33. Receiver-Transmitter, Radio RT-505/PRC-25, top view, modules removed.58

Figure 34. Receiver-Transmitter, Radio RT-505/PRC-25, top view,audio and control chassis A27 open.Section IV. THIRD ECHELON ALIGNMENTNote: Third eche