[RFI] SO2R 2nd Harmonic Interference

[Jim Brown]

On 9/29/2018 1:52 PM, Randall K Martin wrote:
> I tried wrapping the 12V leads of the current charger roughly 10 x 
> through a large toroid and there was little if any reduction in 
> interference. 

Several thoughts. Since you feel a replacement supply is a problem, here 
are some more ideas. Remember that the power line is also a great 
transmitting antenna, so try plugging the unit in to a small extension 
cord and apply the choke (turns on the toroid) to that cord.

Also, how many turns you need will depend on what the toroid is -- what 
mix, how big. A ferrite choke is a parallel resonant circuit, which is 
tuned by varying the number of turns. The resonance will also depend 
strongly on which mix is used. #43 needs a lot more turns than #31, #61 
is next to useless for this. Thicker, longer cores need fewer turns than 
toroids. If you use too many turns, the resonance can be too low.

73, Jim