For many decades, and in the era of electromechanical crypto machines, a lot of the gear manufactured by the Teletype Corporation was used as input /output equipment with crypto gear. Both common and uncommon Teletype equipment is featured here.

The book "The New RTTY Handbook (1962) by Byron Kretzman explains the Teletype trademark.

"Teletype" is a registered trade mark owned by the Teletype Corporation of Chicago and registered August 11, 1925. Although the word "teletype" has come into widespread general use, the lawyers of this corporation still get very unhappy when the first letter is not capitalized when it appears in print. So when we refer to machines made by this corporation, they are Teletype machines. If they are made by another company, they are teleprinter machines.
Radioteletype really got going during World War II. All the services used it. The US Navy called it RATT (RAdioTeleType) and the Army Signal Corps called it SCRT, short for Single-Channel Radio Teletype.
Click on image for more info
19asr_s.jpg 19ASR. It could run at 60 or 75 words per minute by changing gears. The dial was a keystroke counter when  punching a paper tape. You could only have so many characters on a line, then you had to have carriage return and line feed, before starting a new line. (Photo by George Mace)
cdn_embassy_mod28_product_line_s.jpg The 28 product line from Teletype Corp  (circa 1959)
cdn_embassy_mod28_teleprinter_s.jpg 28 Teleprinter
cdn_embassy_mod28_lpr_tape_punch.jpg 28 LPR Tape Punch (circa 1959) .
cdn_embassy_mod28_ldd_td.jpg 28 LDD Transmitter Distributor (circa 1959).
model_28_rt_set.jpg 28RT. Large communications centres used the Teletype Model 28 RT set for the purposes of relaying messages or the storage of messages in transit in communication switching systems.  They were also used for speed conversion.  Many variations  exist.

Click on image to launch the PDF. (Photo courtesy of Teletype Corp). 

tgc1a_2s.jpg AN/TCC-1A Torn Tape Relay. (Photo by Bob Schaefer)
dxd200_s.jpg DXD-200 Teletype Distortion Test Set. (Photo by Jerry Proc)
dxd400_s.jpg DXD400 was the ASCII version of the Distortion Test Set. (Photo by  Don Robert House)
teletype_simple_tester_s.jpg Simple, Portable Teletype Tester. Model # TBA. Approximately 9"W x 6"D x 6"H. It generates single,  Baudot characters based on the settings of the bit switches. It can also can introduce a fixed amount of distortion. (Photo by Jerry Proc) 
td_special1s.jpg TD14 Special.  It has a coded drum that sends "The Quick Brown Fox Jumped Over The Lazy Dog's Back 1 2 3 4 5 6 7 8 9 0" message. (Photo by George Mace) 
xd216_1_front_s.jpg XD216 Dual head TD. (Photo by Bob Schaefer)
/fsl-4_01.jpg FSL-4 Frequency Selective Limiter



45.5 baud 60 wpm  Baudot based equipment - 5 level code.
56.9 baud 75 wpm Baudot based equipment.
74.2 baud 100 wpm  Baudot based equipment machines using 1.42 stop bits (a character comprises of 1 start bit, 5 data bits and 1.42 stop bits). 
75 baud 100 wpm Baudot based equipment using 1 stop bit (a character comprises of 1 start bit, 5 data bits and 1 stop bit). 
110 baud 100wpm For ASCII machines (8 level code)  such as the Teletype Corp 33ASR. (a character comprises of 1 stop bit, 7 data bits, 1 parity bit , 2 stop bits)

All machines made by Teletype Corporation are designated first by Model, then by configuration.  Only third party customers or users  reversed this standard. Why they did this is anyone's guess.  Hence, a Model 28 Automatic Send and Receive set is a model  28ASR, not an ASR28.


Above and below: Students are learning teletype maintenance. When the Teletype machine was king, it took an army of maintainers to keep them running. 

This the 1955 graduating Teletype class at Francis E. Warren AFB, Wyoming. The tall device in the center was referred to as a "Coke Machine" and was filled with typing reperforators. (From the collection of George Mace. He is forth from the left)

Contributors and Credits:

1)  Don Robert House, N.S.E., Bell System Retired. Curator Emeritus NADCOMM.  email: k9tty(at)
2) George Mace <gmace8(at)>
3) Jim Haynes <jhhaynes(at)>
4)  Bob Schaefer <Commtekman(at)>
5) The New RTTY Handbook by Byron Kretzman. Cowan Pulbishing NY, NY.  1962

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June 19/13