[RFI] ebay line filters

[Jim Brown]

On Mon,8/15/2016 6:49 AM, Doug Powell wrote:
> One thing you should realize about line filters is they are optimized for conducted line emissions coming from the product where they are built in. This means the line / load labeling  ‎will determine your best orientation for connection.

There's another MAJOR problem with commercial line filters -- most of 
the trash conducted from equipment is on the GREEN WIRE, which goes 
right past the filter. The specs for these filters CLAIM common mode 
suppression, but what they're calling common mode is voltage between 
neutral and ground. That's NOT what WE call common mode, and what WE 
call common mode is what causes most RFI -- radiation from the power 
conductors as a long wire antenna.

The most effective line filter for MF and HF radio is a common mode 
choke formed by winding multiple turns around a #31 Fair-Rite ferrite 
core, using the guidelines in k9yc.com/RFI-Ham.pdf for coax the same 
size as the power cable. See Chapter Seven the "Choke Cookbook." Also 
see http://nccc.cc/pdf/CQP-RFI2013-2.pdf

73, Jim K9YC