[Elecraft] ferrites for subwoofer: before or after isolation transformers?

[Jim Brown]

On 5/23/2020 5:01 PM, Nicklas Johnson wrote:
> Sadly, it seems like most consumer-grade audio equipment is optimized more
> for cost than for design quality and RFI suppression, even equipment that's
> supposed to be "high-end."  And then sometimes you can buy a piece of cheap
> gear and it rejects RF better than high-end stuff.  Kind of a crap shoot.

For more than 30 years, virtually ALL electronics has been built with 
Pin One Problems. This has as much to do with stupid as it does with 
cheap. When Neil Muncy, ex-W3WJE, now SK, first exposed it in 1994, 
virtually all Pro equipment had Pin One Problems. Every ham rig I 
studied the last time I was in Dayton and last year in Visalia had Pin 
One Problems, including Elecraft.

THAT'S the major reason we need ferrite chokes on all the "receiving 
antennas."  It's also a major mechanism coupling for RF noise OUT of the 
box. The Pin One Problem occurs with the AC "Green Wire" (Equipment 
Ground) and with antenna jacks in home entertainment systems AND in CATV 
and DSL systems. They all put noise on the coax shield and the Green Wire.

73, Jim K9YC