[RFI] Fair-Rite and Tariffs

[Roger (K8RI)]

I (so far) use ferrite cores only for common mode chokes and I've made 
and used many particularly for 160. 75, and 40 center fed slopimg 
dipoles and half slopers.

73, Roger (K8RI)

On 7/16/2019 12:34 PM, Rob Atkinson wrote:
> Many hams blow money on ferrite needlessly, because they see it as
> this magic bandaid bullet for all their RFI problems, whereas an
> understanding of RF and DC will lead them to much less costly
> solutions in a number of cases:
>
> RF on low current DC supply lines:  Inexpensive small pie wound chokes
> which can be found for small change at hamfests can be put in series
> with power supply lines to small appliances at the enclosure to keep
> RF out of shack accessories.
>
> RF audio or relay coil lines can be cured with inexpensive small 0.1
> or .01 ceramic bypass caps to ground.
>
> Audio isolation transformers can be strategically placed to block RF,
> ditto for AC mains isolation transformers which can be found at
> hamfests for a few dollars to be placed ahead of switching supplies or
> other direct rectification supplies.
>
> Opening the shield on multi-conductor lines with it at ground on the
> opposite end can keep RF on the outer surface of the shield from being
> conducted to the affected device.
>
> Ferrite has its uses but should be a last resort.  But I see hams
> spending hundreds and hundreds of dollars on the stuff and trying to
> solve every sort of problem with brute force of ferrite which makes
> vendors happy but may be a waste of money.
>
> 73
>
> Rob
> K5UJ
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-- 
Roger (K8RI)