Operating instructions
fun cti on
switch
is in th e I. F.
position.
Its
output
is
amplifi
ed by Q14 and
Q15,
and
f
ed
to
the
buffer
amplifi
er
in
the
Secon d
IF
and
Di
scriminator
b
oard
wher
e
it
is
mixe
d
with
the
fir
st
IF
s ignal.
4.7
IF O
scillator
Board
Th e
Multi-Oscillat
or
bo
ard
provides
10 r e
cepta
cles
into
whi
ch
IF
oscillator
boards
ma
y be
insert
ed
at
th e
option
of
th e cus to
me
r .
Refer
to
Figure
4-7.
The
frequen
cies
that
ma
y
be
s ele
ct
ed
for
th
ese
crystal-controlled
oscillators
lie
in
ranges
of
from
250
kHz
to 900
kHz
(see
Figure
6-6)
and
from
1 MHz to
13.5
MHz
(see
Figure
6-7).
When
the
fun
ction
switch
is
in
the
I. F.
position,
the I.
F.
GENERA
TOR
SELE
CTOR
may
be
turned
to
one
of
its
numb
ered
posi-
tions
(1
through
10),
thus
a
+20-volt
ener
gizing
voltage
is
app
lie
d to
the
c
or-
resp
on
ding
re
cepta
c leo Th e output of
th e
act
iv
at
ed osci
lla
to r c i
rc
u
it
is
amp-
lifi
ed by
Ql1
and
Q12,
and
is
a
va
il able
at
the
I.
F.
GENERA
TOR
O
UTP
UT
co
n-
ne
ct
or.
If ad
ditional
IF f
re
que nci
es
a r e
need
ed
or
if
it
is
d
esirable
to change
the
frequ
en
cy th
at
is
av
ail
abl
e in a p
arti
cular
po
siti
on of
the
SELE
CT
OR,
r ef
er
to P
ara-
gr
aph
3.
4.5
for
installation
and
remov
al
of
IF
Oscill
ator
boards.
4
.8
Signal-Generator Mixer
Fi
gur
e
6-
8 is
the
sc
he
mat
ic
dia
gram
of the Si
gnal
Gene
rato
r Mixe r . Th e LO
signal
whi
ch
r
ea
ch
es
th e
Signal
Generat
or
l\Ii
xer
from
the
H
armoni
c G
enera
t
or
bo
ar
d
v
ia
th e
coax
ia
l r
el
ay (CH- K1) c
on
si
sts
of
narrow
pulses
with
a
fr
equ
enc
y b
etw
een
28 MHz
and
56 MHz .
This
LO
signal
is
mixed
with
a s ec
ond
input
signal
with
a
10 MHz
frequ
en
cy
fr
om
the
Sign
al
Gen-
erator
Step
Att
enuator.
The
resultant
signals
are
coupled
out
to
the
SIGNAL
GENERA
TOR
OUTPUT
connector.
If
the
desired
sign
al
output
is
below
40 MHz
then
the H
armoni
c
Gen
erator
out-
put
is
high
er
than
the
de
sired
sign
al
by
10 MHz
and
the
low
er
s ideband
is
used,
and
vice-versa
f
or
the
ab
ove.
Th
e
F REQUENCY B
ELOW
40 MHz -
ABOVE
40 MHz
swit
ch
sh
oul
d be
switched
ac
cor
d-
ingly
for
proper
r
eadout.
The
multi-turn
LEV
EL
SET
contr
ol
feeds
a de
voltag
e to
mi
xer-diode
CRl
and
forw
ard-bias
es
it
at
d
if
fe r ent cur -
r
ents
for
ca lib
ra
ting th e
signal
gen
era-
tion
output
in the
differ
ent
co
mmuni
ca-
tions
fr
equenc
y ba nds .
[
[,
4-12
5601"0015"1