US Navy RTTY Equipment - Patch Panels

RTTY is also called RATT (Radio Teletype)


High-level signals are usually 60ma loops (120vdc). 
Low level signals are +/-6vdc. Originally all circuits were high-level until low level signaling was introduced because of TEMPEST concerns.
See here for some more info on low-level signaling.

Red & Black - It is critical that plain text and encrypted text should never be associated with each other. RED refers to signals that represent classified plain text (which need to be hidden from public view). BLACK refers to unclassified plain text or encrypted text (which may be intercepted during transmission). RED and BLACK signals, equipment, and operating areas are kept as separate as possible to minimize the possibility of RED signals appearing in BLACK transmissions. Extensive guidelines for signal routing, grounding, etc. should be followed.

RED teletype signal patch panels are used on the plain text side of encryption equipment and BLACK/GRAY patch panels on the encrypted side. If a piece of teletype equipment can switched between the two, a locking switch and indicator lamp are used to avoid mistakes.

Teletype Circuits - Loop Connection Info

Each loop or circuit contains the following jacks: 

"NOTE: Anyone patching or unpatching circuits from a TTY panel must be sure to pull the plug from the looping jack (LPG) before removing the other plug from the SET (machine) jack. Pulling the SET jack first interrupts all TTY message traffic on that channel. IT ALSO PRODUCES A DANGEROUS DC VOLTAGE ON THE EXPOSED PLUG!"

COMMSTA Patch Panels

This info is from a USAF Relay Center training document, but Navy COMMSTA setups would have been similar

panel-01.jpg (93329 bytes)
Typical Layout
panel-02.jpg (135088 bytes)
Circuit details

More pages - download pdf
Thanks to James Tanton

US Army patch panel info
thanks to Sheldon

High-level (60mA) Patch Panels - Loop Connection Info


includes a switch for each channel to select external or internal loop supply


Manual is NAVSHIPS 91480 (avail from

6 channels
2 LPG, 1 SET, 1 MISC

tt23b-01.jpg (51423 bytes)
photo thanks to WA5CAB

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(Western Electric 63C2)
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SB-6A/GG (Signal Corps)
thanks to Kevin
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Download SB-6/GG manual

4 Channels
2 LPG, 1 SET, 1 MISC

63C1 wiring diagram
thanks to Roy
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sb6-gg-05.jpg (271888 bytes)
Unstamped but a typical USN ID plate
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and USN inspection stamp
sb6-gg-03.jpg (85272 bytes)
sb6-gg-06.jpg (188347 bytes) --


DSCN0159.JPG (5543638 bytes)
SB-1203 aboard USS Midway

sb1203a-ug-201.jpg (44038 bytes)

6 channels
3 LPG, 1 SET, 1 MISC
sb1203a-ug-204.jpg (52819 bytes)
sb1203a-ug-203.jpg (32352 bytes)
More info - schematics, connections, operation, etc.

SB-1203/UG is for black (unclassified) circuits

sb1203-01.JPG (97930 bytes)

manual - 


sb1210a-1605-01.jpg (230878 bytes)

6 channels
2 LPG, 2 SET, 1 MISC

sb1210-02.jpg (26757 bytes)

sb1210-03.jpg (24893 bytes)

More info - schematics, connections, operation, etc.

SB-1210/UGQ is for red (classified) circuits.

manual - 

SB-1210 aboard USS Midway
DSCN0140.JPG (5676011 bytes)


for crypto equipment with step control of TTY tape reader.  

NAVSHIPS 91622 manual
 - thanks to Don N3RHT

3 dual channels
2 LPG, 2 SET, 1 MISC

The special patch cords are dual cords with a pin that matches the hole between the jacks - this prevents getting TTY and STEP signals crossed.

sb2244-ug-10.jpg (2367501 bytes)

Channels 1,3,5 have TTY current control and metering - Channels 2,4,6 have associated "STEP LOOP" indicators. The STEP signal releases the next character from a TD under timing control of the crypto gear.

sb2244-ug-01.jpg (92847 bytes)

sb2244-ug-02.jpg (47527 bytes)

sb2244-ug-11.jpg (2364305 bytes)

Note - as of 5/2016 Fair Radio has this one unused in the box for sale - with manual and patch cords.


24 channels
2 LPG, 2 SET, 1 MISC

sb3576-01.JPG (46800 bytes)  

includes fuses and alarm bell to indicate blown fuse



24 channels
2 LPG, 2 SET, 1 MISC

SB-4034 aboard USS Iowa
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SB-4034/UG interior
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sb4034-2312-02.JPG (4315288 bytes) sb4034-2312-03.JPG (3615395 bytes) sb4034-2312-04.JPG (4020674 bytes) ==
sb4034-2312-08.JPG (5923895 bytes) sb4034-2312-09.JPG (7891584 bytes) sb4034-2312-10.JPG (7079161 bytes) ==


24 channels
2 LPG, 2 SET, 1 MISC

sb4035-470.JPG (1623388 bytes) sb4035-471.JPG (859163 bytes) sb4035-475.JPG (532106 bytes)
sb4035-472.JPG (2715435 bytes) sb4035-473.JPG (1364771 bytes) sb4035-474.JPG (2470592 bytes)
sb4035-dwg-01.JPG (1299193 bytes) sb4035-dwg-02.JPG (4528686 bytes) sb4035-dwg-03.JPG (843514 bytes) sb4035-dwg-04.JPG (833865 bytes)
sb4035-dwg-05.JPG (1391301 bytes) sb4035-dwg-06.JPG (993032 bytes) sb4035-dwg-07.JPG (3309146 bytes)

sb4035-dwg-08.JPG (899282 bytes)

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Teletype Transfer and Power Supply Panels for SSN637 Class Submarines

10 input to 10 output Switch Panels - 
Secure (Red) and Unsecure (Black)

tty-panel-ssn637-02.jpg (1080884 bytes)

tty-panel-ssn637-01.jpg (1316594 bytes) Dual Power Supply with Loop Current Adjust

tty-ps-ssn637-01.jpg (421216 bytes)

tty-ps-ssn637-02.jpg (1282877 bytes)

Low Level (+/- 6v) Patch Panels & Switching Unit


COMMUNICATIONS PATCH PANEL, SB-3145/UG - This communications patch panel is a low-level, send-and-receive teletype, special-purpose patch panel. It is capable of handling 20 half-duplex or 10 full-duplex circuits. Figure 4-21 illustrates the front panel. Jacks and controls are indexed and referenced to descriptions listed in table 4-9. The panel is normally configured for full-duplex, send-and-receive operation. The circuits are numbered 1 through 10, with circuit 1 located on the left side of the panel and circuit 10 on the right side of the panel. Each circuit requires two columns of jacks-one column for send and the other for receive.

For Low-level signals (+/-6v) with 3-conductor patch cords (signals on ring & tip)

Installation drawings


SB-3189B aboard USS Iowa
Secure (Red) TTY Patch Panel
DSC02161.JPG (4100940 bytes)
DSC02162.JPG (4323023 bytes) For Low-level signals (+/-6v)

3-conductor patch cords
(signals on ring & tip)


SA-1794/UG Low-level Switching Unit

SA-1794/UG installed aboard FFG-54
ffg54-11030-sb.jpg (472311 bytes)
SA-1794/UG Teletypewriter Switching Unit Incorporates 6 push-pull rotary switches with instantly removable wafers, low level gold plated contacts, wafers and receptacles, extension capabilities for system expansion, a completely shielded enclosure and minimum size; each unit contains six eight-position switches, mounted in two vertical rows; the positions are six active transfer positions, one extension position and an OFF position; switch position indicating device indicates both the rotary position and the IN position of the knob; when a switching matrix of more than six is desired, additional input or output (or both) devices can be added by using the extension position of the basic switch; systems of any size can be assembled with the multiple use of one basic module.
sa1794-ug-1510-02.jpg (216415 bytes) sa1794-ug-1510-01.jpg (213984 bytes) sa1794-ug-1411-02.JPG (195760 bytes) sa1794-ug-1510-03.jpg (174209 bytes)
sa1794-ug-1411-01.JPG (246151 bytes) sa1794-ug-1411-03.JPG (203840 bytes) sa1794-ug-1411-05.JPG (222910 bytes) sa1794-ug-1411-04.JPG (194536 bytes)

TH-83A/FGC low-level TTY hubbing repeater

TH-83A aboard USS Iowa
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DSC02166.JPG (4170150 bytes) for +/- 6v signals

More info in NAVSHIPS 0967-391-6010

download 38 MB pdf





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Installed on UGC-6 teletype aboard BB-61
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C1004D-01.jpg (149853 bytes) c1004d-02.jpg (186176 bytes)  

similar to C-1004 

no on-off pushbutton switches

wiring diagram of C-1004D installed aboard BB-61 - thanks to Tyler KN6JEB

SA-734/SG Switch and ID-866/SG Indicator

NOTE - These seem a bit confusing. RED normally means classified circuits and BLACK means unclassified circuits.
However, the SA-734 UNCLASSIFIED switch position is RED and the ID-866 UNCLASSIFIED lamp is RED.

Furthermore, I have seen some ID-866 red/green units where the CLASSIFIED indicator is RED and the CAUTION-UNCLASSIFIED indicator is GREEN
This is incorrect - See below.

The reasoning is because these are Teletype machine connections - if you are connected to the UNCLASSIFIED switchboard you need to be careful typing because you will transmit in the clear. If you are connected to the CLASSIFIED switchboard, anything you type will be encrypted anyway. Note that some of the USS Midway switches are labeled SECURE CIR OFF (RED) and SECURE CIR ON (BLACK), which is clearer.

AHA - Here's the spec (MIL-STD-1680C) Lock-out switch visual indicator. The ID-866/SG Indicator Light provides a visual indication of the setting of the SA-734/SG or SA 2371/SG Switch Box. Where the switch box is used for a sharing of processing equipment, the indicator light shall be co-located with the processing equipment for operator viewing. Where the switch box is used as a RED signal line disconnect, the indicator light shall be co-located with the switch box. Visual indicator lamps for Classified or Unclassified, or Classified or Disconnect shall have the following color jewels installed:

  • Green jewel: Color to indicate a classified circuit, or a circuit of higher classification. 

  • Red jewel: Color to indicate an unclassified circuit, a circuit of lower classification, or disconnect position.

I finally got a manual (NAVSHIPS 93757) - 5 MB pdf - and it confirms RED means you are connected to the UNCLASSIFIED switchboard.


id866-sg-03.jpg (25287 bytes)

The ID-866/SG Indicator Light, when used to show the status of a shared RED/BLACK processing equipment, shall derive primary AC. power from the shared equipment to assure the ID-866/SG is energized when the shared equipment is energized.

warning indicators with correct color scheme.

id866-sg-01.JPG (24989 bytes)  id866-1412-03.JPG (186267 bytes)

ID-866 and SA-734 aboard USS New Jersey with the WRONG ID-866 color scheme. 
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SA-734 & ID-866 aboard USS Iowa
with the WRONG ID-866 color scheme
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id866-1412-01.JPG (190710 bytes) id866-1412-02.JPG (222459 bytes) id866-1412-06.JPG (181475 bytes) id866-1412-05.JPG (181560 bytes)


sa734-sg-91.jpg (52576 bytes) TTY switch - key lockout of plug and connections
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sa734-sg-93.jpg (44296 bytes)
ID-866 and SA-734 aboard USS Midway
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sa734-sg-1307-01.jpg (97074 bytes) sa734-sg-1307-02.jpg (107688 bytes) sa734-sg-1307-03.jpg (171295 bytes)


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photos from ebay via Jerry Proc
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  • sync control switch for KW-7
    crypto unit