The AGC circuit in the MFJ 9000 series is WAY too hot. They
recommend setting the AGC voltage pot to +4.5v with no or a
very weak signal. This means that any signal much stronger than
that will cause reduction of gain in the MC1350, including the
long time delay. Then a strong signal comes along, you are
out of gain reductioan range, and the MC1350 goes into gain
comptression. Like the sidetone (a strong signal). This is why
the sidetone is loud and sounds raspy, because you are in gain
compression, clipping the audio and causing distortion.
A quick fix is to adjust the internal AGC gain pot for a pleasing
sounding sidetone. This will end up being an AGC voltage of 5-6v.
This will help keep the MFJ from going into compression on strong
signals and skews the AGC to not kick in until a fairly strong
signal appears.
On my MFJ's, I have a front panel switch for slow/fast AGC. The
slow setting is the MFJ as it is. The fast setting plops a 10K
ohm resistor across the AGC charging cap (or from the AGC FET
gate to ground to parallel the existing 1M resistor). This will
signficantly speed up the decay time of the AGC, which makes a
marked improvement, especially on 40M with QRM, static crashes,
etc. (You know, like most any night!). That long AGC time IS
irrtitating (irritating) on a noisy band. Experiement with the
value of ther 10K resistor to suit your preferrence.
GL, Paul NA5N
PS - using a terminal that the backspace/delete key don't work.
Sorry.
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