USM-481 Test Set VINSON Interconnecting Boxs & Cables

Brooke Clarke, N6GCE


USM-481 with CX-12991
Background 
Component Parts
    Metal Suitcase 
    BA-5590 Battery Eliminator 
    Cable Test Adapter 
Cable Ends 
Manuals 
Links 

Background

Late in the Vietnam era the VINSON voice ciphering cryptographic system as used by the KY-57, KY-58, KYV-2, etc. replaced the NESTOR system used by the KY-38.  There are a large number of manpack, vehicle and airborne installations of VINSON equipment and the USM-481 Test Set was made to troubleshoot those in the VRC-12 family that uses the MT-1029 Mount and the PRC-77 man pack family, like the GRC-160 installations by checking 15 different interconnecting cables and 2 junction boxes.  The following Vehicle installations probably are covered by this test set:

Type
Radios
VINSON
Kit
VRC-12
RT-246, R-422
?
VRC-43
RT-246
Mk-2146
VRC-44
RT-246, R-422, R-422
?
VRC-45
RT-246 w/C-2299
Mk-2146
VRC-46
RT-524
Mk-2146
VRC-47
RT-524, R-442
?
VRC-48
RT-524, R-442, R-442
?
VRC-49
RT-524 w/C-2299
Mk-2146

This box has no classified functionality, it's just a specialized cable tester.  It could be adapted to test other cables by making a different Cable Test Adapter.

The USM-481 will not test most of the cables associated with a SINCGARS RT-1439.

Component Parts

Metal Suitcase

The chassis is made in the form of a metal suitcase that's 18" long, 15" deep and 6" high.  Most of the functionality is integrated into this case and is not removable.  It contains a number of printed circuit boards using discrete parts and CMOS logic chips to test cables and junction boxes for opens and shorts.

BA-5590 Battery Eliminator

USM-481 Batt
                EliminatorThis removable part is a battery eliminator replacing a BA-5590 that will run from 115 or 230 VAC and has a dual 12 Volt outputs with up to 480 mA.  Because there is an A.C. power cord it can not be used inside the battery box of some other equipment.  It is used to power the USM-481 in lieu of using a BB-5590 battery for power.

It's interesting that this eliminator puts put 12 Volts, rather than the 15 Volts put out by the BA-5590, which is labeled "12 Volts" per side.

Cable Test Adapter

This is an "L" shaped metal box with 25 different receptacles, some are plugs and some are sockets.  It can be removed from the suitcase and connected to the tester by means of two cables.

J #
Cable
end
J # Cable
end
Cable

J1
16-26S J2 16-26P
CX-13069
HYX-57 to J-3513-J4
Plain Text wire line ops
4' long

J3
14-19S
J4
16-26S CX-13072
KY-57 to HYX-57
Cipher Text wire line ops

J1
16-26S
J4
16-26S CX-13074
HYX-57 to HYX-57
Cipher or Plain text wire line repeater

J5
GC-239
"P3"
J17
8-4P
"P2"
CX-13062
KY-57 AUDIO  to  J-3513-J1

"CAUTION
CONNECT TO  AUDIO
ON J-BOX ONLY P2"
VRC-64 Vehicle system
to J1 on J-Box
3, 4, 5, 6, 7, 12 or 19 ' long
CX13062
J5
GC-239 J26
GC-329 CX-13073
KY-57 data input to Audio

J6
U-316 J7
14-19S
CX-12991
PRC-77 POWER  to  KY-57 RADIO
GRC-160 Man Pack only
30" long
CX12991
J8
14-5S
"P5"
J16
8-3P
"P4"
CX-13063
HYP-57 Pwr In  to  J-3513-J2
7 Ft.
"P4
CAUTION
CONNECT TO POWER
ON J-BOX ONLY"
VRC-64 Vehicle system
3, 4, 5, 6, 7, 12 or 19 ' long
CX13063
J9
14-19S
J15
12-10P
CX-13100
?

J10
U-316 J13
16-26P
CX-13067
J-3513-J4 <-> J-3514-J3
2, 4 or 5' long

J10
U-316 J14
14-19S
CX-13061
J-3513-J3  to  KY-57 RADIO
VRC-64 Vehicle system
3, 4, 5, 7, 12 or 19' long

J11
MW10M
J13
16-26P
CX-13068
used with C-10374 (Off - Retrans box)
3, 5 or 9' long

J12
16-26P
-
-
"A" Cable  to  URM-481

J18
16-26S
J23
U-316 CX-13071
HYX-57 RADIO/KY  to  PRC-77

PRC-77 end of a wire line link
CX13071
J19
  • U-316
J20
J23
  • U-316
  • U-316
CX-13065A
3 ends connects:
J-3513-J6, AM-2060 Set Pwr, PRC-77 power
VRC-64 Vehicle system
Marked in this order:
(end) J3513-J6 ("T" connector) RT-841 (end) AM2060
CX-13065
Stub J21
cable
J26
GC-283
CX-13075
"Y" cable like for an H-161 or CVC helmet

J22
16-26S
-
-
"B" Cable to URM-481

J24
  • 12-10P
"J3513(J6)"
J25
J26

  • U-316
"X-mode"
  • GC-329
"RXMT"
CX-13064
"Y" cable

CX13064

Testing J-3513 & J-3514 Junction Boxes

When the Cable Test Adapter is disconnected from J12 and J22 junction boxes can be tested using the cables that are a part of the URM-481 main chassis.

J-3513

Junction box for use with MT-1029 and RT-246 or RT-524.
What about the AM-2060 & PRC-77?

The J-3513 fits "upside down" between the base of the MT-1029 and the equipment shelf.
J-3513A
                        Label side
J-3513A
                        Right Side

J #
Cable
end

J1
8-4P

J2
8-3P

J3
U-316

P1
?-18S

J4
16-26P

J5
U-229

J6
U-316
J7
?-17P

J3514

Junction box for use with MT-1898 and R-442 Receiver.
Fits between the base and shelf.
J #


J1
?-9P

J2
8-4P

J3
U-316

J4
8-3P

P1
?-9S


Cable Ends

14-19S

Mates with the RADIO connector on the KY-57.

U-316

Mates with POWER connector on PRC-25, PRC-77.
Mates with the X-Mode connector on the RT-524/RT-246.
Probably many other radios have this same connector.

16-26S

Mates with RADIO/KY connector on HYX-57.

GC-239

Mates with U-329 6 pin AUDIO cable connector.

U-229

Mates with the 5 pin AUDIO connector on most radios.

Manuals WANTED

TM 11-5810-345-12
TM 11-5810-345-24P SRA/VINSON Interconnecting Box Test Set, AN/USM-481
TM 11-5810-345-34
If you have any manuals or other information please let me know how I can get copies.

Links

Crypto Machine Training-

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