Advertisement
Transistor Q18 is used to couple 38KHz
@
90
0
into the Subchannel
filter to produce the GEN
0
indication.
CRI. CR2. Ul and Q6 provide the Pilot Present Lamp threshold detect
functions.
6.
A6 (SeA) Assembly
Compos;
signal is buffered by 01 and fed to the dual 67KHz
lter.
One section of this filter
has a bandwidth approximately 1KHz
and fulfills the FCC specification for exact measurement of SeA injection.
The output of this filter
ion is buffered by Q2 and fed to the DISPLAY
EeT switch.
The other section of this filter has a wide bandwidth to
allow injection measurements under modulation and also to prevent unwanted
composite signal components from reaching the SCA demodulator.
U2 is a
phase locked loop demodulator.
The audio output
is
buffered by
06~
filtered
and
ampl; ed by Ul and U4.
changes the 100% deviation point from 4KHz
to 6KHz depending upon the front panel SeA DEV switch.
U3 determines SCA presence and also drives the SeA frequency output.
07
mutes SeA audio if the SeA
is
lost.
Q8 and Q9 drive the SeA PRESENT
lamp.
7.
All (Display Select Switch) Assembly
This seven station pushbutton selects the signal component to
displayed.
U1 and associated circuitry form a high pass active filter
with a low frequency cutoff of 50Hz used
the FM SIN position.
Ll is a
19KHz fil
that smoothes the PILOT
0
CAL null indication.
Advertisement
