KX1 speaker output with superimposed oscillation

[wb2srf]

Try changing the value of R21 from 2.7K to 4.7K

I had a similar problem with load sensitive parasitic oscillation of the
LM386 with a Norcal 40
When this happens it can block the receive signal because of the agc
action.

The (high frequency rolloff) feedback may be causing enough phase shift
to cause the amplifier to oscillate.

Hope this helps

GL 73,
Bob Johansen WB2SRF
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[Francisco Barros]

Hi Bob,

Hate to say it, but it has the same behaviour with the new value of 4.7k for
R21: the audio signal shows the parasitic oscillation just on the negative
peaks, even with a 10 uV RF level.

In any case, many thanks !.

73,
Paco

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