[GreenKeys] AN/FGC-38 Torn-Tape Relay Equipment

Sun Aug 27 01:26:19 EDT 2017

The AN/TGC-1s were generally referred to as "Chesters", since
they often resembled a chest of drawers by their shape and design.

We had a few TGC-1s in Europe in the early 60s. Operators did not
normally get in each others way, since an operator was often assigned
to a "bank" of about 3 or 4 Chesters to work. Rather than one op  moving
from one Chester to another to send or receive tapes, it was common
practice to toss tapes from one op to another. In order to do this,  tapes
were hand-rolled into a figure eight and either handed to a bank op  by
an expediter (an expediter is a person who moved traffic within the  relay
bay), or tapes were sometimes just tossed back and forth if the  working
ops were in close proximity. When tapes were handled by an expediter,
they were NOT rolled into the figure eight; he wore them around his  neck
bandolier style as he moved from position to positon or operator to  
operator. 
As he moved around the relay bay, he read the Routing Indicators to where  
the tape(s)
were destined and then delivered the tape(s) to the appropriate  operator,
or hung it on the tape holder for that circuit. (Routing Indicators == Sort 
 of
like a Call Sign in the tape relay world consisting of a series of letters  
(no numbers
or figures unlike ham radio Call Signs). See ACP-121 to understand  Routing
Indicator formulation and ACP-117 Routing Indicator Lists.

The idea of an op being assigned to work a set or bank of Chesters was 
precisely to keep them out of each others way, since clustering  around
one of these things was awkward at best given their engineering and
design placement. Recall that the TGC-1s were the first production 
military tape relay gear, so everything was evolutional.

The Chesters first came out in early WW II (1942) and lasted thru the early 
 1960s.
These were Western Union machines (probably produced by either
Teletype Corp or Western Electric originaly), for the US Navy. They  proved
so successful for high volume traffic movement that the Army and Army Air 
Corps and later Army Air Force adopted them as well. Many were  mainstay
relay equipment during the Korean War and were used by all of the  services,
even the then newly created, separate US Air Force. After WW II,  several
other models of tape relay gear came along to replace the Chesters,  and
thus, much of this equipment was never standardized until about the  time
the Vietnam War era began (in the Army, it was Kleinschmidt, and by then  
everyone
was making Kleinschmidt clones for the Army: Singer, NCR, etc to meet
the wartime demands. For the Navy, it was Teletype Corp, Hamilton Watch  Co,
and perhaps a dozen other companies producing Teletype Corp models.

FWIW, you could NOT run a tape relay using ASRs....and there was no
need for a printer in a tape relay operation, since it was all "tape"  
relay.
Where printers existed in a relay, they were for occassional monitor  copy,
or for online coordination between relay and trib, or for order wire, or  
for Service 
positions only.

Dave

# # #

In a message dated 8/25/2017 5:47:23 P.M. Pacific Daylight Time,  
jhhaynes at earthlink.net writes:

Thanks  for posting that.

There are two basic architectures for torn-tape  switching.  One is 
represented by the AN/TGC-1 which has the  reperforators and the 
transmitters in the same cabinet.  The other  has the reperforators
in one set of cabinets and the transmitters in  another, as in the
FGC-38.

An advantage of torn tape switching in  general is that the routing
information is all done by humans, so it is  easy to adapt to a situation
where routing is changing frequently or  requires a lot of intelligence
to figure out.  The disadvantage is the  need for operators to handle
all that tape manually.

The AN/TGC-1  architecture is advantageous in situations where switching
centers must be  established or moved or expanded or cut down quickly.
It has the  disadvantage that the routing operators get in one another's
way, and that  it is extra footwork to involve a routing desk in the
process.  So the  FGC-38 structure is advantageous for more fixed 
installations and larger  installations.

It is very common in this kind of switching to have one  outgoing line
fed by two tape transmitters, arranged so that only one at a  time can
be sending while the other waits for the one in use to reach the  end
of tape.  This allows keeping the circuit busy without the  operators
having to wait for a reader to finish.  Typically there is a  holder to
allow a whole bunch of tapes to be queued on a sending  position.  I've
heard of situations where there were wires like  clothes lines strung
across the switching room, and tapes awaiting sending  humg on them with
clothes pins; but later more to-the-purpose hardware was  developed.

Postal Telegraph Co. had a system in which there was a  hidden reperforator
and tape transmitter associated with each outgoing  line.  The idea was
to clear the switching floor transmitters quickly  and let messages queue
up in the hidden reperforator.  This might have  been undesirable in a
military situation where a high precedence message  might pre-empt a
lower precedence message already in  transmission.

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