[Elecraft] Snap-On Ferrites and RF Noise On 160M

[Bill Coleman]

On Apr 19, 2010, at 12:37 PM, Jim Brown wrote:

> On Sun, 18 Apr 2010 19:00:19 -0400, Bill Coleman wrote:
> 
>> I found that putting a snap-on ferrite core around the power cord reduced 
>> the spur to an S5 indication. A similar reduction could be had by placing 
> 
>> snap-on ferrite around the power output leads.
> 
> Study my tutorial on RFI and ferrites. 
> 
> http://audiosystemsgroup.com/RFI-Ham.pdf 
> 
> Most snap-on ferrites are designed for maximum effectiveness in the 150 MHz 
> range. ANY "snap-on" ferrite is next to useless on 160M unless multiple 
> turns are wound around it.

Please read the whole posting. The snap-on ferrite was used as a diagnostic tool. It showed a reduction in the unwanted signal on both the AC mains and the output power leads. Even if the snap-on ferrite was not the optimal final solution, it was useful in identifying where the energy was being radiated from the box.

I did not use snap-on ferrites in my eventual solution to reduce the RFI. 

Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Web: http://boringhamradiopart.blogspot.com
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901