Nortel Networks 553-3001-211 manual Wire DX signaling 143, Circuit

Circuit

	Distant circuit			External
electromechanical (may also be				loop
Succession 1000M, Succession				(5kΩ max.)
	1000, or Meridian 1)
Ð 48V	600Ω	400Ω		Tip A
	370Ω	370Ω	B1	a	T2 (Note 2)		J5
				Ring A			R A
Balancing	See Note 5		See	b		See	1.21kΩ
resistance	6µF	4µF			4µF		(Note 4)
			Note 5 Tip B			Note 5
(see Note 3)							R B
				a	T1		1.21kΩ
	370Ω	370Ω A1		Ring B			J3

250Ω b

1kΩ

Ð 48V

A

Ror

D1

Local system circuit

Ð 48V

RC 1100Ω

	R C	R E	State of
	130Ω	750Ω	trunk
K1			detector
	R F

130Ω 130Ω Req (Note 1)

600Ω

K1

48

R

4-wire	Figure
DX signaling	143

NT8D15

Card Description and Installation

Note 1: The equivalent bridge circuit resistance as seen from distant trunk during the signaling is 1250 ±125 Ohms.

Note 2: T1 and T2 resistance is 47 Ohms for 600 Ohm termination option.

Note 3: Compute total balancing resistance as follows (note that in some new DX circuits, a 1260 Ohm resistor is permanently wired in series with the selectable resistance). Total balancing R = external loop resistance + 0.5 x T1 resistance + 0.5 x T2 resistance + [(RA + RD) if not shorted out] + Req. Resistance of transformers at electromechanical end is low and can be ignored. "External loop resistance" is defined as 1/2 the loop resistance of one cable pair.

Note 4: If the external loop is >2500 Ohms, the loop adjustment resistors RA and RB are shorted out. If the external loop is <2500 Ohms, RA an RB are in the circuit. When the system is connected to another Meridian 1 or pulse and external loop resistance is <2500 Ohms, the loop adjustment resistors must be shorted in one machine. If the external loop is >2500 Ohms, the loop adjustment resistors must be shorted out in both machines.

Note 5: When the system is connected to an electromechanical trunk using 4-wire operation, a 4µF capacitor must be connected from the A1 to B1 lead at each end of the trunk. (These may already be installed.) It is also recommended that a 6µF capacitor be connected in series with the balancing resistance.

553-AAA1151

E&M Trunk card Page 625 of 894