Hi Bob,
Finally, I got it !.
It is related with the RC network connected between the output pin 5 and
ground, required to keep the amplifier stable at high frequencies at
different loads, as you mention on your previous post.
I checked the RC network and I even installed a new one: same
Hi Dave,
Thanks to you.
IHope Bob can tell us, with the modeling of the LM386, why this strange
behaviour.
From the knowledge point of view, the technique try and error is not the
best way, we would like to know more... .
Now, my KX1, at the LM386's speaker output, pin 5, has the original RC
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
Hi to all,
After alignment and Test - Part III, I got more power on 20 m (3.8 W) than
40 m (3.2 W).
As the manual says, for best harmonic rejection, it should be the opposite
(0.3...0.6 W more power on 40 m).
Following some previous posts (thanks Don), I checked very carefully all the
Hi Don
First of all, thanks for your answer.
Well, I have checked it also with a signal generator: the output signal at
R3 (AF Gain) R5 junction is always a clean 2,2 Vpp 600 Hz tone, with RF
levels of 10 uV till 500 uV, except at close or maximum volumen. I this
case, even with a 10 uV RF
Hi to all,
The scope shows a superimposed high frequency oscillation just on the
negative peaks of the audio signal.
It produces a distorted and annoying audio when the signal peaks, specially
when listening a loud station on the external speaker.
This happens when the volume is close to or at
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