[GreenKeys] RADIO TELETYPEWRITER AN/GRC-46

[WA5CAB at cs.com]

The vehicular set was actually AN/VRC-29.  The primary component of 
AN/VRC-29 and AN/GRC-46 is AN/GRC-19.  The primary component of AN/GRC-142 is 
AN/GRC-106.

In a message dated 8/2/2010 9:59:04 PM Central Daylight Time, 
NNN7DXB at aol.com writes: 
> To expound a bit on what Duncan just mentioned:
> 
> For those who don't know, the AN/GRC-46 is a Radio Teletype set (rig)
> that was originally mounted on the M-37 series 3/4 ton truck. The
> AN/GRC-46 was used primarily by the US Army in tactical units. Power
> was supplied by a 5 KW generator set on a trailer. This equipment was
> in use until about 1969. After that, it was superseded by the AN/GRC-142
> which was an upgraded model with the same capabilities. Primary
> Teletype equipment was Kleinschmidt TT-98/FG printer and TT-76/C
> Reperforator-Transmitter (TD), or any of their variants. Crypto gear
> was the usual TSEC/KW-7 - for both the AN/GRC-46 and AN/GRC-142.
> Operating speed was normally 60 wpm (45.5 Baud). Some European
> export models were set up for 66 wpm. These rigs were common in 
> the Army and could be found in Signal, Infantry, Artillery, Armor,
> Quartermaster, Aviation and Test and Eval units. They were used
> for message handling in most units, for spotting, targeting &TACFIRE
> in Artillery units, and for Aviation Weather operations in Army Aviation
> units. Most times, they were employed in Army Command/Operations
> and Administrative/Logistics RATT nets. Often times, they were
> co-located with tactical CommCenters in the field environment as one
> of the (commcenters) various means sections. More than AN/GRC-46
> or AN/GRC-142 were in proximity when working with commcenters.
> When commcenters circuits went down, RATT picked up the slack;
> When commcenters were swamped with traffic (especially Routine
> traffic), that traffic was moved over to the RATTs which as overflow.
> Most RATTS in tactical units were redundant to most tactical commcenters;
> this means, where there was a tactical commcenter, there was also
> a RATT at the same location, so traffic could always mover over either
> RATT or the commcenter, commcenter being the primary system of
> choice. Both the AN/GRC-46/142 were One-Way-Reversible (OWR)
> operations only, or what we in the commcenter usually called "half 
> duplex".
> You could only send or receive at a time, but could not do both with the
> same equipment. These systems worked on High Frequency (HF) only.
> Later model AN/GRC-142s had provision for a wire-line "pony" circuit
> to the commcenter, which was usually unsecure (since the RATT and
> commcenter were inside the same SECURE perimeters when operating
> together).
> 
> On the Y side (DSSCS), RATTs were used for Intel traffic to pass Exercise
> COMINT traffic in the field; they also passed intercepted G-2 Weather
> traffic and sometimes supported Corps and Division SWO operations.
> In Europe, Russian Weather from RUMS was often intercepted by G-2s
> at both Corps and Divisions levels. RUMS was the call letters for a large
> and powerful HF Russian weather transmitting station in Vladivostok 
> during the Cold War. It transmitted synoptic WX data at 60 wpm, clear 
> text.
> (The Russian RUMS not to be confused with the large US Army tape relay
> at Phu Lam, with the Routing Indicator RUMS, 1959 thru 1970).
> 
> These rigs could also be used for passing tactical Intel (enemy sightings,
> grid coordinates for patrols, and other tac-intel operations in the field;
> as well as other Intel Operational and Informational traffic). The AN/GRC-
> 46s and 142s did not handle GUARDRAIL traffic, nor did it support any
> of the TROJAN operations in the tactical units.
> 

> Hope this helps.
> 
> Dave
> 

Robert & Susan Downs - Houston
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