[TenTec] cabling question re TT 253 tuner

[Jim Brown K9YC]

On Fri, 15 Aug 2008 09:16:46 -1000, Ken Brown wrote:

>I suggest you use the best RCA phono cables you can find, or build you 
>own using RG-58, so that you know what kind of shield they have. 

This whole issue of cable shield quality and RFI is a red herring. The 
REAL issue is improper connection of the cable shield at the equipment!  
The ONLY good connection of the cable shield is directly to the 
SHIELDING ENCLOSURE (the chassis). The the cable shield gets to the 
chassis via the circuit board, you've got common impedance coupling into 
the circuitry of whatever RF current is flowing on the shield. This 
design error is known in the audio world as "the pin 1 problem," and is 
the MAJOR cause of RFI both in ham gear and consumer gear. Most TenTec 
gear has a pin 1 problem at every RCA connector. 

It IS good to have a BEEFY (low DC resistance) shield on AUDIO cables, 
because that reduces the IR drop from power-related noise currents 
flowing on the shield. But that is the ONLY good reason for using RG58 
for this purpose, and ANY cable with a beefy copper shield would work 
just as well. 

73,

Jim Brown K9YC