Re: Bitx40 very loud, high-pitched, low frequency noise

Gordon Gibby

You may decide that you want to build a real low pass filter, with an inductor etc., similar to what people had to use in the past to get rid of alternator whine 

On Aug 23, 2019, at 14:39, SP9DEV <piotrekslawecki2@...> wrote:

Alright, time for a follow-up:

I've added two 47nF (0.094uF total) ceramic caps, one 330pF ceramic cap, one 10uF electrolytic cap and another one 100uF cap across the DC input. Unfortunately, the problem is still there.

However, I've assembled a simple 12V battery from one 9V battery and two AA batteries. With this as my power supply, the problem is gone. I can still hear some faint noise, but that's probably due to the fact, that I've been testing this setup right next to my PC, two monitors and a lot of other RFI-generating stuff. So I guess the only way to deal with my problem is to buy a large 12V acid-lead battery and a dedicated charger.

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