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Model 5245L
cable leading
to
the
trigger
on the function control
assembly
A21.
The loaded twisted cable optimizes
voltage
gain,
minimizes capacity effects, and isolates
signal ground
current.
See
Figure
7-1?
for circuit
details.
2-9L.
FUNCTION CONTROL ASSEMBLY
A21.
2-92.
GENERAL.
The
function control
assembly,
Figure 2-17, switches the counter logic
circuits
to
perform the
various counting
functions. The
signal
which
is
counted by the
decimal
counting assemblies
is
switched
to
the high frequency trigger by
one
of
the
input gates; 1, 2,
4, or
6.
The
resulting pulses
are
gated
by
the main gate
and
then
drive
the 50 MHz DCA,
A1?.
The
signal to control the main gate
is
switched
to
the
period trigger by input
gates
3
or
5.
The
re-
sulting pulses either drivethe gate control assembly,
M2
dftectly
through gate 12
or
are divided by
the
decade
divider
assemblies
and
then
drive the
gate
control through gate
13.
2-93.
SIGNAL
FLOW.
The following outline gives
signal flow
for
each
measurement
function.
In
each
case the control signal to the main gate
is
on
during
counting.
a.
MANUAL.
The input signal
from
A19
passes
through
gate
2, amplifier
Q1, high frequency
trigger
Q3-Q4, pulse amplifier Q9, main
gate Q10-Q11,
and
pulse
amplifier
Q13
to the gated signal
output.
b.
MANUAL
CHECK.
Same
a
s
MANUAL
except
gate
2
is off
and
gate
1
is
on
so
that the selected
fre-
Section
II
Paragraphs 2-91 to
2-93
quency
from
decade
dividers
passes
through to
gated
signal
output.
c.
FREQUENCY. Input signal path same as
f
o
r
MA}{UAL.
Selected
frequency passes
through gate
3,
emitter follower
Q2, period
trigger Q5-e6,
and gate
L2
to the
gate
triggering
output.
d.
FREQUENCY CHECK.
Same as
for
FREQUENCY
except
gate
2
is off
and
gate 6
is
on so
that a 10
MHz
signal passes to gated signal
output.
e.
PERIOD.
Selected
frequency
from
the
time
base
controlassemblyA3S passesthrough gate 1,
Ql,
trig-
ger
Q3'Q4, Qg, main
gate Q10-Q11,
and
Q13
to
the
gated
signaloutput.
The
input signal
fromQl9
passes
through gate 5, Q9, period
trigger
Q10-q11,
and gate
t2
to the
gate
triggering
outputs.
f.
PERIOD
CHECK.
Same
as PERIOD
except that
gate 5
is off
and
gate
3
is
on
so
that the selected
fre-
quency (always
100
kHz
for
PERIOD
CHECK)
from
the
time
base
control
assembly A35 passes
to the
gate
triggering
output.
g.
MULTI-PERIOD.
Same
as PERIOD except that
gate 12
is
off
and gate
13
is
on.
The output
of
the
period trigger
Q5-QO
is
divided
by
the
chain
of
decade
dividers.
The output
of the proper divider drives
the
multi-period trigger Q7-Q8,
and
passes through
gate
13
to the gate triggering
output.
h.
MULTI-PERIOD
CHECK. Same
as
MULTI-
PERIOD
except that gate 5
is
off
and
gate 3 is on
so
02349-L
05 245
-B
-4
SIG.
INPUT
FROM AI9
GATED
SIG
TO
At7(2)
RATIO
HF
INPUT
FROM
A2O
IOMHz
FROM A35
GATING
SIG
FROM
A22(9)
SEL
FREO
TO
A2
SELECTED
FREQ
FROM A35
MULTIPLIED
PERIOD
SIG WHEN
MULTI-PERIOD
AVE
FROM
A35
PERIOD
SIG
TO
A35
GATE
TRIGGERING
TO
422(8)
Qlo,Qil
MAIN
Figure
2-t7.
Function Control Block Diagram
2-19
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