[Amps] The Pin One Problem

[Jim Brown]

On 6/6/2013 10:05 AM, Peter Voelpel wrote:

> The pin 1 problem generally is not a problem with the gear but with the external wiring

Actually, it is a problem built into equipment by a 
designer/manufacturer who fails to terminate a cable shield for external 
wiring to the shielding enclosure, but instead to interior wiring 
(usually a circuit trace). The most common way this happens is that 
connectors are mounted to the circuit board, not to the shielding 
enclosure. This manufacturing defect is nearly universal in consumer 
electronics of all sorts, in nearly all ham gear (except antenna 
connectors), in most semi-pro audio and video gear.  I still see Pin One 
Problems on the exhibit floor of audio and video trade shows.

The Pin One Problem is addressed by AES48, which can be downloaded from 
www.aes.org.  There is a fee for the download for non-members. There is 
also considerable detail at k9yc.com/publish.htm

Fundamentally, The Pin One Problem couples common mode current into 
equipment, where it is then detected and added to the signal. 
Corresponding suppression for unshielded wiring should typically include 
chokes on the conductors and bypass or feedthrough capacitors to the 
chassis.

73, Jim K9YC