The Components of the KnightSMiTe
                    (The Audio Amplifier)

** C15 **

C15 provides a DC block and couples the detected audio at the
emitter of Q2 to the input of the audio amplifier U1.

U1 along with C11 through C14 and R6 complete the receive
portion of the KnightSMiTe.

** U1 **

The audio amplifier (U1) increases the level of the detected
signal voltage 200 times and provides sufficient output power to
drive low impedance headphones or a small speaker.  This self
contained audio processing stage is the primary source of
amplification in the receiver (46 dB compared with a measured 4
dB conversion gain in Q2 operating as an active mixer).

** C11 **

C11 provides an audio bypass at the emitter of the input
differential amplifier stage of the LM-386 audio power amplifier
IC.  This reduces emitter degeneration from 1.5 K-ohms to 150
ohms at audio frequencies effectively increasing the voltage gain
of the input stage (and thus the amplifier chain) by a factor of
10 without increasing the quiescent DC current drain.  A short
circuit (jumper) here would achieve the same result with a
tenfold increase in DC bias current but no improvement in
performance.

Reducing the value of C11 will degrade the low frequency response
of the amplifier.  Reducing this to 1 ufd or even 0.1 ufd may be
desirable if a sufficient transmit offset is achieved.  Stations
that zero the calling frequency must be at a sufficient offset to
produce a tone in the 1 kHz frequency range or higher to overcome
the degradation in low frequency response of the audio power
amplifier that would result from this change.

Adding a 1.5 K-ohm potentiometer in series with C11 will provide
an effective audio gain control but this should not be a
requirement with the KnightSMiTe since the receiver derives most
of its gain here and all of it is required for detection of weak
signals.  Gain control can be introduced here if the volume is
objectionably high.

** C12 **

C12 works in conjunction with R6 to stabilize U1 and prevent
motorboating (low frequency oscillation) when connected to a low
impedance load such as an 8 ohm speaker or headset.  Together,
they serve as a phase shift network to prevent the amplifier from
becoming unstable.

** C13 **

C13 serves as a DC block and couples the audio amplifier (U1)
output to the speaker or headset.  It's value is large to
maximize the low end frequency response of the receiver.

** C14 **

C14 is optional but enhances the noise immunity of the audio
power amplifier especially at high gains.  It is nothing more
than a bypass capacitor used to minimize noise that may be riding
on the power supply from becoming amplified by the high gain
input stage.  A higher value capacitor here (on the order of 10
ufd or better) might be used to reduce hum on the output if using
a poorly filtered AC power supply.  Its value is non-critical,
however a large reduction in value may degrade the low frequency
response slightly and increase susceptibility to local broadcast
interference.  A larger size would result in a larger size
package and consume valuable board space.