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