I'm not that specialized! :( if I have a pattern, a design in front I follow it, but I can not say that! I already struggle with the translation ...
Da:[email protected] <[email protected]> per conto di Dexter N Muir <dexy@...> Inviato: martedì 17 aprile 2018 10:46 A:[email protected] Oggetto: Re: [BITX20] Help me! annoying ticking in the audio #bitx40help
?
I've watched the video, and noted that ticking increasing in level at low volumes. I venture this is an instability similar to that sometimes present in the Bitx-40, solved by a resistor (1 to 10k) from Vol-wiper to IC 'in' pin. Now the TDA chip is 2 amplifiers,
and it's likely both are unstable. Voltmeter pin 1 (AC range) or o'scope, and you'll likely see the 'blips'you hear, and then on pin 3 constant blips.
Cure: replace R75 with 2k2 or so (solving the high-level), and similar 2k2 pin7 to VOL-M and top of C78 (break that track) to solve the low-level...
