Technical note 4

Pigtails, the sting is in the tail

Leakage (stray) inductance causes power leakage from or into low-impedance signal connections. The leakage inductance of screened cables varies from less than 1 nH/m for 'semi-rigid' and 'double-braid' coaxial cables to about 15 nH/m for low-quality antenna or SCART cables.
Compare this to the inductance of 1 nH/mm of pigtails, connector pins or printed wiring; these parts are often 25 mm or longer and thus completely spoil the performance of even low-quality screened cables.
The length of the pigtails, the unscreened sections in connectors and receptacles and the unshielded printed wiring completely determine the performance of screened cable connections.
Pigtails of 20 mm have a stray inductance of about 20 nH, far more than that of screened cables.
It is useless to apply well-screened SCART cables: the ground connections in the unscreened connector („l 40 mm), the receptacle („l 30 mm) and the wiring on the printed wiring board (often 100 mm or longer) have a stray inductance of 170 nH or more and completely spoil the performance of screened SCART cables.