Re: uBitx has a bit too crispy / semi-distorted audio even on low signal levels #ubitx #ubitx-help


Did the biasing mod. That solved the crossover distortion issue. I took a 500 ohm pot and paralleled that with a 125ohm resistor. The mod doesn't look so good  (LOL) but it works. One of the transistors became warm if the voltage difference due to the pot became too large. I adjusted this while feeling the temp and listening to  a cw carrier: low distortion AND low temperatire, became the setting point.
(Disregard the screened cable in the lower left of the pic. That was the tap to my external amp, before biasing the original amp more properly).

Join to automatically receive all group messages.