Len,
That sounds like AGC recovery - which is on the slow side in the KX1.
To be certain that is the cause, monitor the voltage at U5 pin 2. It is
normally 0.6 volts with a maximum signal and 1.4 volts with no signal.
If this voltage increases as the audio level increases, it is the AGC
that is reducing the gain.
I doubt if the AGC itself is the problem, this is only a check to know
whether or not the AGC is being activated and thus reducing the audio.
Now, if you do find the AGC is reducing the gain, you then need to
discover what is causing the AGC to be activated after transmitting -
when you have that answer, you have found the real problem.
One possible cause is a non-functioning Q7 (that transistor reduces the
signal level into the receiver during transmit).
73,
Don W3FPR
Len Revelle wrote:
> Newly returned to the reflector and couldn't formulate a good search
> parameter in the archives so my apologies if discussed before.
>
> Broke out the KX1 to play with FD and noticed that, after switching
> from TX to RX, audio/sensitivity intermittently rises from very quite
> to normal levels. This "recovery" takes about 2-3 seconds. I've tried
> to replicate the cause and it seems to defy me. Anyone run into this
> and found the cause?
>
> I'd forgotten how much fun this thing is.
>
> Len Revelle N9IJ
>
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