 |
|||
|
|
|||
|
|
|||
| ||||||||||
|
|  injection subunit (sect. III) through injec-
resistor R123. Tuned circuit Z104 pro-
tion contacts 6 and 7 of relay K102 (closed
vides a high coupling impedance for the
on receive), jack J112, and capacitor C135.
rf signal.
b. Capacitor C119 grounds rf at the grid
The uhf injection signal heterodynes with
of V103. The +125-volt dc plate voltage is
the received rf signal to produce the 20.0
to 29.9-mc difference frequency, which is
supplied to V103 through rf choke L107.
Capacitor C120 bypasses rf signals from
coupled directly to output jack J102 through
the +125-volt dc supply. Resistors R105
injection relay K102, contacts 3 and 5. Jack
and R110 return the grid of V103 to the rf
J106 is a test point for checking the first
avc bus. Capacitor C116 bypasses rf sig-
receiver mixer injection.
nals to ground. The rf signal is amplified
c. The first receiver mixer V104, re-
by V103 and coupled by capacitor C121 to
ceives plate voltage from the +125-volt
parallel-tuned tank circuit Z105 and var-
supply through plate load rf chokes L109
iable capacitor C122. Jack J105 is a test
and L113. Choke L113 and bypass capac-
point for measuring rf avc voltage.
itors C134 and C136 decouple rf signals
from the +125-volt dc supply.
16. Tuning
a. The rf signal voltage developed
across Z105 is coupled to the cathode of
first receiver mixer V104 by C123. Re-
When tank circuits Z101, Z103 and Z105
are tuned by the frequency selector, both
s i s t o r R111 provides cathode bias for
V104 through rf choke L110. Capacitor
capacitance and inductance are varied;
C125 is a cathode bias bypass capacitor.
this improves the selectivity by maintain-
Capacitors C137 and C144 ground rf at the
i n g the proper inductance-capacitance
grid of V104, and resistors R106 and R107
( L C ) ratio. Trimmer capacitors C107,
provide grid leak bias. (On transmit, R107
C115, and C122 set the minimum capacity
points of the tank circuits. The 1,800-
is short-circuited by contacts 9 and 17 of
position shaft of the frequency selector
tr relay K601.)
b. A 200- to 370-mc signal is also ap-
tunes the three tank circuits through the
225.0- to 399.9-mc frequency range.
plied to the cathode of V104 from the uhf
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals