Construction: how to shield CPU noise?


m_a_schuster
 

I'm not talking about noise from a nearby computer. I'm referring to hash generated by the radio itself, which then finds its way into the audio output.

 

Rare on Tecsun radios, I've seen it with cheaper brands but most especially with Degen models. Also Kchibo. Why some brands/models handle it well, and others not, is a mystery to me.

 

Sometimes it can't be fixed easily. The Ccrane pocket radio suffers from it. Their solution: add a button to turn of the display. Hmm. Well, it works.

 

Case in point: the Degen DE-11 (Kaito KA-11), an aging, tiny little PLL multiband styled like previous better-made Sony models. All of MW, and a good portion of SW, is drowned out by buzzing unless you have an S9 signal.

 

If one would attempt to add a shield, where would you start? At the source (CPU? display driver chip? how to identify) or the target? Any generic pointers from someone who has successfully tackked this kind of thing.

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