Re: pop click pop on tuning BITX40

John Cardoso

Thanks David and Dexter for your good effort and time.
Unfortunately nothing seems to work and I do not understand why the good souls at HFSignals do not fix this since it seem to be a well know problem. 
Meanwhile they keep selling this kit without the fix. And that is not right (in my book).
The pops are really loud. I mean it - really loud. These are not just "innocent little clicks" these are really loud pops.
Well, love it or leave it, right?!

On Thu, Jun 13, 2019 at 12:55 AM Dexter N Muir <dexy@...> wrote:
Known problem since Bitx40. The Arduino takes  more current to make its change, creating a current spike on the power rail. The cure is to absorb some of the power drop in the Raduino's 5V regulator leaving it some 'headroom' to actually do its job (it's typically run close to its maximum power rating). Typically a 5 (4.7 or 5.6) ohm resistor does the trick: it needs a 3-watt rating. Put that in series with the Raduino's 12V supply, with a 100uF 16V electrolytic capacitor to Earth (0V) across it at the Raduino. That way the 100uF Cap supplies the energy rather than the whole supply, so that main supply is not drained for that brief instant. (Theory for the advanced: a 500uS RC filter).

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