[GreenKeys] RADIO TELETYPEWRITER AN/GRC-46

[NNN7DXB at aol.com]

HI Duncan:

The idea of operating any of the Army's RATTs "mobile" was largely
a designers idea. Matter of fact, after 1966 or so, the concept of 
operating any of these rigs mobile (as in convoy formation) was
prohibited because of a serious incident that occured in Frankfurt,
Germany involving an AN/GRC-26D and German trolley car wires 
in downtown Frankfurt. The GRC-26D involved was blitzed beyond
repair and the 2 operators seriously injured when the whip antenna
came in contact with the overhead trolley wires. The trolley system
was shut down as a result for several days. The incident involved
the 32nd Signal Battalion out of Hoechts (McNair Kaserne) in
early 1966 during a day move to the field. The GRC-26D was part
of a 2nd March Unit (2nd convoy involving a Corps "Main" deployment).
(in the 50s and 60s, German trollies (street cars) ran in the streets;
overhead wire lines were common. In the 70s, these were eventually
moved underground and became the subway systems (U-Bahn) networks
that exist today).

Operating mobile also created problems with grounding of equipment
on wheeled vehicles. There were provisions for grounding, but they
rarely ever worked as intended. Ungrounded commo gear (esp TTY)
garbled all to hell).

Soon after this incident, MACOMS were advised NOT to operate these
types of rigs on the move, especially in cities, towns and villages. I
don't recall who issued the order, but it was widely followed by all
V ad VII Corps commands after 1966. The Canadian Army in Germany
(4th CMBG, HQ & Signals Squadron, had a similar nasty experience
operating mobile in the Baden Wurtemburg area using an AN/GRC-142
in the early 80s. They too issued similar orders to stop the practice.
When I was in the 1st Inf Div (Fwd), 3rd Bde, we were paired with the
Canadian units often, and frequently interoperated in Signal functions
with them. They used the same equipment as we did.

The VRC track mounted RATTs were permitted to operate, but had
to follow the same operating guidelines as jeep (M151) mounted
RT-524 FM radio systems  using whip antennas. There were further
restrictions in that the track-mounted RATTS could only operate
during day time, and only in "open field" areas where there were
no wire lines. In most Army commands, especially in Germany,
VRCs generally did NOT operate on the move during peace time
or during Cold War field maneuvers. I am sure that in real war-
time conditions, they would have operated. There were some
occassions when we operated RATTs inside our M-577 Command
Tracks "on the move", but generally, this was only to copy or 
monitor traffic, and not to send (i.e. not to key the transmitters).
(With all the banging and crashing inside a moving track, it was
virutally impossible to "poke" (type) any message traffic; you could
not even sit in a chair without getting tossed out most times, so
most guys just hunkered down until we stopped and set up camp.

Other considerations were that Germany has a LOT of forests. US
Army units traversed these forests, and as a result, bobbing whip
antennas (made of fiber glass) often broke, snapped, cracked or
were so severely damaged that trying to operate "mobile" was just
not practical. Too much unsustainable damage to the antennas resulted.
Some units tried pulling antennas down with a clip, so that the whip
was facing "backward". This too was impractical, becuase it greatly
diminished reception on the move for HF. Even so, antennas still
got broken.

Another consideration from my experience with moving tracked
vehicles is that usually - you moved around in those things "buttoned
up". You (the operators) couldn't see outside; only the driver and
the TC could see, and they generally went where the rest of the march
unit went, rather than selected their own routes. Antenna-friendly
routes in the field were never a consideration on their parts.

The performance on the move with Kleinschmidt teletype gear
was less than gratifying at times, esp with the TT-98s which could
not stand up to the banging around inside of the track (which often
offered an extremely bumpy and rough ride). I don't recall the 28VDC
electrical system (memory fades); seems the M-577s had a 4.2 KW
generator mounted topside.

The M-577s often went "off road". They went where most of our
wheeled vehicles dared not go, and were generally assigned to different
March Units than the wheels.


The AN/GRC-122s and GRC-142s could be operated with most
late model trucks, mostly GAMMA Goats using a 100 amp kit which
turned the vehicles 3-cylinder diesel engine into a generator. The 
drawback to this was that this kind of operation could only be done
during the halt, and not on the move. The 100 amp kit did not work
while the vehicles engine was being used as the prime mover. Some
Signal units used M-880s or similar commerical-type pick up trucks
in later years that had the 100 amp kit, although I never worked
with any of those. Nearly all wheeled vehicles that were equipped
with the 100 amp kits - also pulled a 5 or 10 KW generator trailer.
The trailer often carried 2 generators (either 2 5 KWs, or 2 10 KWs,
plus at least 5 ea 5 gal gas cans and the proverbial "donkey dick"
feeder system).

I never worked with the GRC-26D or the GRC-46s using any onboard
power. My time, we always used 5 and 10 KW trailer mounted gas
generators, same stuff used with AN/MGC-17s, AN/MSC-29s, et al.
Sometimes, the entire Command Group used a 600 KW diesel 
generator that powered everything....

Dave