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
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