Military Teleprinters
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Teletype radio plane set, used by Navy Dept., to receive typewritten radio messages from Naval airplanes
Created / Published
1922 Aug. 30.
Format Headings
Photographic prints--1920-1930.
Library of Congress Catalog Number




Teletype Operator's School Scott Field 1950

Minor comment on Signal Corps practices. Unlike USN, Signal Corps equipment nameplates show the Order Number. A Signal Corps Contract was a generic document that basically authorized a contractor to accept Orders and get paid for them. The (usually) last two digits in the Order Number are the last two digits of the Federal Fiscal Year. Which from the first FD Roosevelt administration until the first Reagan administration ran from 01 JULY of the previous calendar year to 30 JUNE of the year listed. So if the Order Number is dated 1951, depending on lead times and available stock on hand, the first deliveries could have been in the second half of 1950. Especially if it was a re-order.


My 2 cents worth regarding the TT-4.....
The TT-4 (A) was a 1949 design. It really wasn't designed to replace the Model 15s in
use at the time (TT-5), but was more or less accepted by the Army as it was purpose-built
to be both "tactical" and "light weight", compared to all the other clunkers available
at the time. This was predicated on the fact that the Army had approached the Teletype
Corp to produce light weight equipment for use in the field by the Army. Teletype Corp
said "no" to the proposal because their (then) current lines of equipment were so
successful, both commercially and militarily, and their production lines were at 100%
capacity (they had no more production capability and could not expand or increase).
Note also that the Model 15/19 designs dated from the mid-1930s, and likely the
Army wanted something a bit newer in the post WW II period. The Army also wanted
something that was a "military" model, or at least military-specific, since this was
going to eventually become a DoD-wide equipment-design system in years to come.
A year or two after the TT-4 came out, Kleinschmidt brought out the early model
of the TT-76 as a complimentary piece of equipment to go with the TT-4. This
essentially replaced the Model 19s (TT-7s) iniatially in tactical installs and later
in some fixed stations. The TT-4/TT-76 combinations worked pretty well for the
Army, although, for some years, it was common to (still) see combinations of
older Model 15 printers working with the newer TT-76s, or Model 14 reperfs working
with a TT-4, especially in later-era AN/GRC-26B RATT rigs.
(Prior to the introduction of the TT-76, there existed a Teletype Corp perforator
(I don't recall its' designation or model number). This machine was widely used
in field applications because it was light weight, small, and consisted primarily
of a standard Teletype Corp Model 15 motor, standard Model 15 keyboard and
a tape perforator.....and was used to simply cut tapes. There was no TD or printer.
(We still had a few of these in Germany in the early 60s -- excellent little machines).
Many of these older and newer machines were used in fixed CommCenters as
well, in all types of configurations and combinations.....
The Army however, was not entirely satisified with the TT-4/TT-76 machines for
fixed CommCenters. No one really knows why. A refined version was produced.
We later knew it as the AN/FGC-25X, which was billed as a complete "ASR" set
(unlike the TT-4/TT-76 which were separate components and not a "set", and which
could be combined with other, older models of equipment).
It was the later TT-98 (TT-100) that actually replaced the Mod 15, and as most of
us know, the TT-98 and TT-76 were "standard" configurations in most tactical
assemblages in later years. Some fixed stations also used them, and -unofficially-,
these combination machines were billed as AN /FGC-21s). (The real AN/FGC-21
which did exist, was an entirely different machine using the same components,
but also a mixer unit from a Model 19 for use with the PYTHON One-Time tape
encryption system).



Looking thru my "stuff" in regard to the early TT-4s, it is likely the Army's bigger
need at the time was for a small, light weight printer for use in the field in a time
before all of the factory-built comm shelters came into being.....
Recall that during WW II and thru most of the 1940s, teletypewriters were used
mostly at Corps level and higher in the field, largely due to their extreme weight
and bulk. Most of the equipment then in use was commercial-grade Model 15/19
gear. Such equipment did not lend itself well to either fast-moving tactical units,
nor to the dust and dirt, and rough handling normally associated with military
field duty. One must understand that the Army, especially during training
maneuvers and exercises, always preferred the nastiest, harshest, most
undesirable climates, weather, and the like for troop training. The assumption
here is that THAT was how real wars were likely to be fought anyway, and both
the troops and their equipment had to stand up to it.
The concept of the field teletype probably started with the Army during WW II.
The "field" teletype was usually set up in one of two configurations:
a. a teletype machine(s) set up and operating in the back of a 2 1/2 ton truck,
usually without a shelter or van assemblage. Most of these truck-mounted
teletypes were simply set up in the bed of the truck -- under the canvas cover
of the truck itself with whatever electrical and signal lines running from a ground
location to the equipment in the bed of the truck. Very primitive by the standards
we got to know later on when factory-built shelters came into being.
b. a teletype, usually a Model 15 (printer) might also be set up the same way,
but in a tent. Sometimes, more than one Model 15 might be in use at the same
time ("different circuits").
Both of these set-ups were likely the forerunner of what later became the
AN/PGC-1. The AN/PGC-1 was essentially a TT-4 printer, a wooden crate that
it was packed in, and operating accessories (paper, ribbon, etc). Once set up
in the field, the wood crate became the table on which the TT-4 was set for
use. Not sure if the AN/PGC-1 included a Terminal Telegraph unit (TH-5) which
would have served as an early, tube driven, "modem" of sorts.
Both the Army and the Marine Corps used the AN/PGC-1 in the field.
In these configurations, there were often no off-line tape prep capabilities. Most
traffic processed might be 'received" from somewhere else, usually higher HQ.
Any traffic that had to be "originated" was usually typed online directly by the
op. The concept of the self-contained CommCenter had not yet been developed.
Neither had the separation between "tactical CommCenters" and "Radio Teletype"
operations, as both were more or less considered one and the same.
During the Korean War, things began to change. Shop-built shelters came along
to house and operate this equipment. Most of these were made of wood and looked
like huts placed on the back of a large truck. As time developed, the huts were
refined for different types of uses by different types of units and by the end of the
Korean War, several variations has been produced and were in regular use by Signal
So far as I know, the first mobile or tactical teletype shelters used by the Army
were the highly successful AN/GRC-26A series and most of these were used for
early HF RATT. These rigs were mounted on the bed of a 2 1/2 truck and were
provided with a trailer-mounted 5 or 10KW generator for power which the truck
pulled. Models of trucks varied over the years from the old G735 Diamond Rios
to the late-date M-35A1s and 2s thru thye 1960s when the GRC-26s were finally
phased out (culminating in the AN/GRC-26D which contained all Kleinschmidt
teletype gear). All of the GRC-26-series shelters were of wood construction, were
weather-proofed and held up well under heavy field use. A few later models featured
some metal sides and roofing.
Along with the GRC-26s came other shelters, these being intended for teletype
operations other than RATT. The most notable here was the AN/MSC-29
CommCenter van, which used the same prime-movers and generator sets as the
26s, but which had considerably more teletype equipment installed (aboug 16 pieces
of Klineschmidt gear, 8 TT-4s and 8 TT-76s, plus the capability for crypto gear,
Terminal Telegraph equipment, a field telephone switchboard (SB-22), a small
safe, a small desk, operating accessories, patch panels, power hocks, and
purpose-installed outside binding posts for various line and circuit connnections.
The AN/MSC-29 was a unique piece of equipment in that is was designed for
multi-purposes. At Division and Corps levels, it could be used as a field tape
relay van, or it could be used as a terminal station. In any event, it had a great
deal of capability and could support 4 full-duplex or 8 half duplex encrypted
TTY circuits. Having worked in these vans extensively over the years, they were
common equipment and "staples" of many signal units throughout the US Army
for many years, including the Vietnam War years. As the need for teletype service
and message traffic increased over the years in field units, it was common to
see two (2) AN/MSC-29s set up back-to-back operating a large Signal Center
at Division level, or in the case of an Army Corps, with as many as 28 of them lined
up in 2 rows, also back to back, operating a field Major Relay station (i.e. as with
VII Corps, 34th Sig Bn in Europe).
I do not believe any other services operated the AN/MSC-29s.
Aside from the 29 vans, the Army had, over the years, developed many other
teletype vans. Not far behind was the Air Force which developed its' own line of
CommCenter vans (and the Air Force also used the AN/GRC-26Ds in the early 50s
and 60s, but theirs were usually mounted on an International Harvester commercial
truck bed, in a day long before the ground-mobile "mobilizers" came along.
I can find no record of the Marine Corps ever using the larger Army-style vans.
Likely, these would not have been practical for an assault force on the move,
but they worked fine for a slower-moving occupational force, or for units in
semi-fixed (static) situtations in a field or fixed environment.
Hope this info is helpful,





Kleinschmidt manuals available at

It looks like the contract date is "51", so it was probably made in the mid 50's. In 1967 in RVN, the Army was using TT-4A, B & C models. The TT-4 was the new Kleinschmidt Co.'s first product and was accepted by the Signal Corps as their standard teletypewriter c1950 to replace the Teletype Corp. M15.

Note the hooks on the side of the bottom plate that are not used to secure the cover. They are to allow you to strap it to your pack frame for "easy" transportation! (after all it is "portable": TT-4 is major component of AN/PGC-1)

Looks like a "parts" machine, or leave the cover on!






Our country-wide commcen at Long Binh, Vietnam used the TT-4s and TT-76s exclusively. We had four land-line
teletypes and one RATT link. The attached photo shows the land-line teletypes in our bunker. 

This photo was taken in 1971 at Long Binh, RVN.  This commcen supported HHC, 1st Aviation Brigade.  we used KW-7s with the plugblock version.  See: for detail on the KW7 if you are not familiar, or just want to re-aquaint  with this crypto system. .


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1978 ECI E-Systems T-1148 Military Impact Teleprinter Print Ad




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