[GreenKeys] RADIO TELETYPEWRITER AN/GRC-46

Wed Aug 4 11:13:50 EDT 2010

Interesting story, Duncan.

Since the discussion veered off into operating the AN/GRC-26D while in 
motion, I thought I would add this.  I was stationed at Ft. Riley, Kansas in 
1965-1967, at a fixed station HF transmitter site.  At some point we were 
issued an AN/GRC-26D, probably because it was really fixed station equipment 
mounted in a large shelter mounted on a deuce-and-a-half truck (2 R-390 
receivers, CV-116 converter, and T-368 transmitter).  I liked to fiddle with 
it, so I ordered the missing technical manuals and spare tubes and fuses to 
bring it up to complete condition.  Some reserve unit got a really nice rig 
when they transferred it.

Anyway, I thought it would be fun to see if it would work while driving down 
the highway pulling its 5KW generator on a trailer.  As I recall, the reason 
mobile operation was not recommended was that exhaust fumes from the truck 
might enter the shelter.  We picked a nice day when we could leave the 
shelter windows closed, and took off down I-70.  My memory is that we drove 
for about an hour before the signal faded out.  The antenna was held 
part-way down with a nylon rope.

If you've ever been to Kansas, you know that trees are seldom encountered. 
In most places, you can't even SEE a tree.  Also, I-70 runs in pretty much a 
straight line from Missouri to Colorado.  In this specialized case, the gear 
worked fine!

Paul Pennington
Augusta, Georgia

----- Original Message ----- 
From: <NNN7DXB at aol.com>
To: <duncanancy at earthlink.net>; <greenkeys at mailman.qth.net>
Sent: Tuesday, August 03, 2010 9:41 PM
Subject: Re: [GreenKeys] RADIO TELETYPEWRITER AN/GRC-46

> 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
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