I will try to follow your advice! If you refer to the transistor mounted alongside the raduino, it heats up a lot !!!
Now I have made a new discovery! He receives nothing! Whether with an antenna or without changing anything! :(
Now I will try to check all the welds on both boards.
What I do not understand is that they must provide me with a working product! If I want to improve it then it's my thing! They say that every card is numbered and tested! But mine ???
Da:[email protected] <[email protected]> per conto di Dexter N Muir <dexy@...> Inviato: mercoledì 18 aprile 2018 22:33 A:[email protected] Oggetto: Re: [BITX20] Help me! annoying ticking in the audio #bitx40help
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Acknowledged, Raj.
The regularity of the ticking points to the processor loop due to the old library. Upgrade to latest (CEC?) firmware fixes that.
My point, however, is the vulnerability of the audio circuits. The LM IC of the Bitx-40 was vulnerable to instability (not always evident) as the 'in' pin got taken to ground by the volume control wiper, and that 'bottom-end' increase here indicates that same
vulnerability. I venture the increase at higher volumes is likely 'bleed-through' from the unused channel - its 'in' pin has a low resistance to ground, and it could well be constantly 'ticking', not evident until the 'used' channel's input sees higher impedance/resistance
of the pot.
Better regulation/filtering of the Raduino's power improved much in the Bitx-40- this 'ticking' (as frequency was changed), and overall stability. How hot is your 7405 regulator, SaMa photo SaMa photo? Mine got quite hot, dropping 5V (12V less the 5V out and
2V 'overhead' for effective regulation), so quite possibly running near its limits. Dropping that input voltage to about 8V with a resistor (a scrapped 51-ohm 3-watt did that nicely) gave the opportunity to better filter its input with a good hefty capacitor
(I had a scrapped 1000uF to hand, 200uF didn't quite 'cut the mustard'), meaning any 'impulse' from the Raduino (the si5351) had less chance of getting through to the main board's supply.
I'd seen reports of distorted audio at low levels, too, and that was cured with the vulnerability/instability by the resistor to the 'in' pin. Now, if the TDA chip has a similar input circuitry it may well have that same vulnerability - on both channels! QED.
Hope the convoluted logic makes some sense ...
73
Dex, ZL2DEX
