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Section
II
Paragraphs 2-60 to
2-68
c.
WithA5,
connects
output
of
first or
second
deci-
mal counter (A16
or A1?)to trigger-circui.t
of
oscilla-
tor
assembly
when
in
SCALER position.
d.
Provides AC
ground
through bypass capacitor
for
signals
not
selected
as
input
for trigger-circuit
of oscillator assembly.
2-60.
OUTPUT
SWITCH
ASSEMBLY
A5.
2'61.
The
output switch assembly (designated OUT-
PIII
on
rear
panel) includes
an
amplifier
stage
and
a
nine-position switch(.1
Hz
thru
10
MHz
and
109
thru
10
in
decade
steps).
Circuit details are
shown
in
the
schematic
diagram, Figure
7-6.
Switch functions
are listed belor:
a.
Provides standard frequency signals
at OUTPUT
connector
from
counter
time
base
if
MODE srvitch
is
not
set
ts
SCALER
position.
Normally provides all
frequencies
from
.lHz
to
10
MHzin
decade
steps but
frequencies of
100
Hz
and
belourare
interruptedwhen
counter
is
reset,
and
availability of
frequencies
of
1
kHz and below depends
on
setting
of
FIINCTION
switch.
b.
^Provides
scaling of input signals byfactor of
10
to
109
(in
decade ste-ps)
ai
ttte
burpur
connector
when MODE switch
is
set
to
SCALER
and
FI]NCTION
switch
is
set
to MANUAL
START.
c.
Amplifies
selected output
for
aII
selections (ex-
cept standard frequencies
of
1
MHz and
10
MHz
and
scaler
ratioof
10and
100;
amplifier
isdisabled
by+13
volt bias
supplied
when
these outputs
are
selected).
2-62.
Po\ilER SUPPLY: RECTIFIER ASSEMBI,YA6;
2-63.
GENERAL.
Several supplies
are
included
in
the
5245L. Their
characteristics are
tabulated in
Table 2-2.
Note
In the folloring
discussion complete
refer-
ence
designations
are
used to
identify compo-
nents.
This is to prevent
confusion
between
reference designations
of power-suppty com-
ponents located onthe
chassis
and
components
located on
the rectifier assembly
(AG)
and
regulator assembly (A?). For
example,
"R1"
would refer
to a
component
located on
the
chassis,
while "A?Rl"would
refer to
a com-
ponent located
on the regulator
assembly.
Complete designations
are
used when con-
fusion might exist
between
chassis compo-
nents
and
circuit-board
components.
2-t4
Model 5245L
Table
2-2.
Power
Supplies
Supply
Regulated
Remarks
-15
v
+13
v
+20
v
-130 v
+1?0
v
Yes
Yes
Yes
No
No
Series reg
Series reg
Series reg
-150
v ref to
+20
v
+150
v ref to
+20
v
2-64.
PRIMARY
POWER. As
shorpn
in Figure
7-7
either
115-
or
230-
volt AC
power
is
connected
through
an
LC
filter
(C5A, C5B,
L1, L2),
fuse F1
and
front-
panel po$/er switch
S3B
(part of SAMPLE RATE con-
trol)
to the
primary
of pover transformer T1
and
T2.
Moving slide switch 54 on the
rear
panel
to the left
exposes
rr115rr
and connects
the
primaries in parallel
for
115-volt operation. Moving the slide switch to the
right
exposes rr230'r and connects the
primaries
in
series
for
230-volt
operation. Transformer
T1 sup-
plies
power
for
continuous
operation of the
crystal-
oven-heater control
circuitsl
note
that turning off
the
counter
does
not
turn off the po\perto the crystal
oven.
Fan motor
81
is
connected
across a single primary
winding; T2
functions as
an
autotransformer to
supply
115-volts
to
81
when
the
instrument
is
connected
for
230-volt operation.
2-65.
I/IINUS
15-VOLT SUPPLY. The regulated -15
volt
supply consists
of a
full-wave
rectilier
(AOCRI
through AOCR4) whose output
is
smoothed
by
filter
L3-C6, regulated
by
Q2, and
further filtered
by
A?C2.
The A?R4, A?R5,
A?R6
divider
supplies
a sample
of
the
regulated output
to
A7Q2
which amplifies
and
inverts variations in the sample. The
A?Q2
output
controls driver
A?Q1
which in
turn
controls regulator
Q2.
Potentiometer A?R5
permits
adjustment of
the
regulated output voltage by providing a
means
of ad-
justing
A?Qz
bias.
2-66.
REGULATOR
OnERATION. Operation
may
be
traced as
follows:
Suppose
the
output
voltage
tends
to
shift
torpard
-14
volts.
This
causes t}re
voltage
at
the
A?Q2 base
to
go
in
a
positive direction resulting
in
a
decrease
of
conduction
and
a
negative swing
in
A?Q2
collector
voltage;
driver
ATQ1
increases con-
duction
(A?Q1
emitter
and Q2 base
voltage go
negative);
regulator Q2 increases
conduction
and returns
the
output voltage
to
-15 volts.
2-67.
OTHER REGULATOR COMPONENTS.
Break-
dorpn
diode A7CR1 provides
a 6.8-volt
reference to
the emitter of A?Q2.
The A7R1-A7C1
network pro-
vides phase correction
for
stability during transients.
2-68.
-130 VOLT
AND +1?0
VOLT SUPPLIES.
Two
conventional
full-wave
rectifiers
supply unregulated
+1?0
volts and -130
volts.
Each
rectifier circuit
pro-
vides
a
150-volt output (filtered by C?
and
C8), but
the circuits are
referenced
to
+20
volts
so
tfie actual
output voltages
(relative to
ground)
are
+1?0
volts
and
02349-1
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