[Amps] RF on audio using 374A

[Jim Brown]

On 9/14/2011 8:35 AM, Jim Barber wrote:
> Bob, if you're tracking this and happen to have a mic that will plug
> into the balanced mic input on the 5000A, it would be interesting to
> know if that has any effect on the issue. (assuming you're not already
> using the balanced input)

A balanced input is no cure for a Pin One Problem -- indeed, the entire 
concept of a Pin One Problem was first observed and identified by Neil 
Muncy, ex-W3WJE, with BALANCED inputs of pro audio gear. The Pin One 
Problem is simply a cable shield that does not go directly to the 
chassis, but instead goes to the circuit board and then, eventually, to 
the chassis.  It is what happens on those "ground" or "common" circuit 
traces that are The Pin One Problem. Neil published his work as an AES 
Paper in 1994, and was later elected a Fellow of the AES.

73, Jim Brown K9YC