Specifications

(1)
(2)
(3)
4
Figure 1. Audio amplifier, schematic diagram.
Transistor Q7602 receives its in-
put from the secondary winding of
T7602. The input signal is coupled
to the base of transistor Q7602
through capacitor C761O.
The output signal of Q7602 is de-
veloped across a tuned circuit con-
sisting of inductor L7603 and ca-
pacitor C7612. Resistor R7609
reduces the Q of the tuned circuit
to provide the proper bandwidth.
Resistors R7606 and R7607 form a
voltage divider which provides the
fixed-biasing portion of the
emitter-base bias for Q7602. Re-
sistors R7608 and R7605 establish
the self-biasing portion of the
emitter-base bias and stabilize
the emitter current. Capacitor
C7609 is an rf bypass capacitor for
resistor R7605. Resistor R7608
pro vi d es emitter degeneration
which stabilizes the stage. The
stage is also stablized by the out-
of-phase portion of the signal fed
to the emitter of Q7602 from the
tapped secondary winding of trans-.
former T7602. Capacitor C7611, in
conjunction with the bottom half of
secondary T7602, neutralizes the
second 11.5-mc amplifier. Capac-
itor C7605 and inductor L7602 form
a decoupling network in the +16-
volt dc supply line.
d. The output from the second 11.5-mc
amplifier is rectified by diode CR7602 and
filtered by capacitor C7613. The dc voltage
is taken from potentiometer R7611 and fed
to the Schmitt trigger circuit. The amount
of dc output voltage to the Schmitt trigger
can be varied by adjustment of R7611.
5. Filter, 5.65-Mc
(fig. 39)
Filter FL7501 is a bandpass crystal
filter having a center frequency of 5.65-
mc. The filter is in series with the output
of the test probe rf preamplifier circuit
when switch S7902 is in position 12. It is
a part of assembly A7500. The filter has a
minimum bandwidth of 5.4 kilocycles (kc)
at the 3-db points, a maximum bandwidth
of 6.6 kc at the 6-db points, and a maxi-
mum bandwidth of 12.2 kc at the 50-db
points. Its input and output impedances are
50 ohms. Its insertion loss at 5.65 mc does
not exceed 6db