Specifications
portion of the emitter-base bias
and stabilizes the emitter current.
Capacitor C7703 is an rf bypass
capacitor. Capacitor C7702 and in-
ductor L7701 form a decoupling
network in the +16-volt dc supply
line.
c. The output from the 5.65-mc ampli-
fier is rectified by diode CR7701 and
filtered by capacitor C7705. The dc output
is taken from potentiometer R7708 and fed
to the Schmitt trigger circuit. The amount
of dc output voltage to the Schmitt trigger
can be varied by adjustment of R7708.
7. Amplifier, 47.0-Mc
(fig. 4)
The 47.0-mc amplifier is a two-stage rf
amplifier. Overall gain of the two stages is
about 15 db. Power, input, and output con-
nections to the 47.0-mc amplifier are made
when selector switch S7902 is in position
18. The output from the 47.0-mc amplifier
is rectified and fed to the Schmitt trigger
circuit.
a. The first 47.0-mc amplifier uses
transistor Q7702 in a common-emitter
stage.
(1)
The input signal from the test probe
(2)
of transformer T7702, trimmer
capacitor C7708, and fixed capac-
itor C7715. Resistor R7710 re-
duces the Q of the tuned circuit to
provide the proper bandwidth.
Resistors R7709 and R7711 form a
voltage divider which provides the
fixed-biasing portion of the
emitter-base bias for Q7702. Re-
sistors R7712 and R7713 establish
the self-biasing portion of the
emitter-base bias and are used for
c u r r e n t stabilization. Capacitor
C7707 is an rf bypass capacitor
across R7713. Since only a portion
of the self-biasing network is rf
bypassed, the input impedance of
Q7702 is effectively raised. Coil
L7702 and capacitor C7710 form a
decoupling network in the +16-volt
dc supply line.
b. The second 47.0-mc amplifier uses
transistor Q7703 in a common-base stage.
(1)
(2)
The ‘signal appearing at the sec-
ondary winding of T7702 is coupled
through C7709 to the emitter of
Q7703. The output of Q7703 is
coupled through C7712 to the tuned
output circuit which consists of
coil L7705 and capacitor C7713.
Resistor R7717 reduces the Q of
the tuned circuit to provide proper
bandwidth.
Resistors R7716 and R7715 form a
Figure 3. Amplifier, 5.65-mc, schematic diagram.
6