Lesson 3/Learning Event 6
(3) On the other hand, if the plug is patched to the LINE jack, the
plug "looks" toward the attenuator and breaks the circuit from the VF
amplifier.
(4) A VF monitor (MON) jack is always in parallel with a circuit, and
therefore never breaks a circuit in either direction.
It monitors the
signal passing in either direction through a circuit.
VF MON jacks are
not wired normal-through.
Learning Event 6: DC JACK CIRCUITS
Tactical communication systems use wire pairs for teletypewriter
circuits, one wire in each pair providing the metallic return circuit.
Strategic
communication
systems
use
single-wire
ground
return
arrangements. Moreover, all circuits passing through the DC patch boards
use single-wire ground return.
When tactical system pairs are brought
into the van through the appropriate 26-pair cables, one wire of each pair
must be grounded at the combined distributing frame (CDF) so as to
maintain the single-wire concept through the van.
Battery for the DC
circuits can be provided either by the communicating teletypewriters, by
the telegraph terminals, or by the AN/MSQ-73.
Simplicity and uniformity
of operation is most conveniently achieved by arranging the AN/MSQ-73 to
furnish battery.
a. Interconnections.
Basically, the AN/MSQ-73 is an interface unit.
No circuits terminate at the van.
The circuits enter and leave the van
through 26-pair cable connectors, and are connected through send and
receive patch panels. The dual function of these patch panels is testing
and circuit patching.
Since two DC patch panels are provided, the
technical controller can test in either direction of transmission. All DC
jack circuits in the AN/MSQ-73 are arranged for full-duplex operation
only; message information therefore always flows in one direction through
one jack circuit, and in the opposite direction in another jack circuit.
Relays are provided for circuit isolation when incompatible telegraph
circuits are to be connected. If the circuits are compatible, relays are
strapped out of the circuit. Each relay can be independently arranged in
different configurations, such as neutral in and neutral out, polar in and
neutral out, polar in and polar out, and neutral in and polar out.
Normally the relays operate as neutral in and neutral out.
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