All drawings appearing in this Recommendation have been done in Autocad.

ANNEX A

(to Recommendation Q.552)

Example of a longitudinal interference coupling network

The component should be chosen with small absolute tolerances (at least resistors and capacitors with 1% and the inductance with less than 5%) and matched to pairs where relevant to achieve a longitudinal conversion loss better than 60 dB at 1000 Hz. For this LCL measurement a terminating resistance of 600 Ohms symetrically applied to each port should be used.

Figure A-1/Q.552 - T1105730-87

TABLE A-1/Q.552

Components list

Quantity

Type

Metallized resistors

1

10

R1 . . . R10: 100

ohm 1%, 1.1 W

2

4

R11 . . . R14: 49.9

ohm 1%, 1.1 W

3

12

R15 . . . R26: 133

ohm 1%, 0.35 W

4

12

R27 . . . R38: 32.4

ohm 1%, 0.35 W

5

2

R39 . . . R40: 24.9

ohm 1%, 0.35 W

6

4

R41 . . . R44: 200

kohm 1%, 0.35 W

Styroflex foil capacitors

1

4

C1 . . . C4: 15

nF 1%, 160 V

2

8

C5 . . . C12: 7.5

nF 1%, 160 V

3

4

C13 . . . C16: 28

nF 1%, 160 V

4

2

C17 . . . C18: 24.3

nF 1%, 160 V

5

2

C19 . . . C20: 20

nF 1%, 160 V

6

2

C21 . . . C22: 499

pF 1%, 160 V

7

12

C23 . . . C34: 60.4

nF 1%, 63 V

HF-chokes, ferrite rod

1

2

L1 . . . L2: 47 mH 5%, Ro 1.1 ohm