Re: Ubitx V4 opinions?
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Gordon Gibby
¿ªÔÆÌåÓýWell there actually is some feedback, it is in the form of those emitter resistors in the final audio amplifier. R75 R77The crossover distortion may be that in order to properly bias those transistors ¡°on¡±, just a bit of emitter current has to flow, creating a voltage drop across those two emitter ?resistors (e.g. choose 10mA * 4.4 ohms=44mV), which is not accounted for
by the Voltage drops across the?diode¡¯s on their base side.
Current through R75 should be about 0.6 mA.
Suggests added series R = 44mV/0.6mA= 75 ohms
Gordon (back of the envelope calculation¡¯s)
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