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OUTPUT
SYSTEM ASSEMBLY
4.71
For
example, on Range
5,
if
the
i
octave
logic signal (pin
8
)
is
high,
Q5
will
be
turned
on and
also
Q4,
thus reverse biasing
D4
and
forward
biasing
D
1
.
This
allows
the
r.f.
signal
to
pass
through the
filter
formed by
the stubs 17
and
18,
with
C13,
C14
and C15.
Since
Q3
will
be
off,
diode
D2
is
reverse biased,
which
blocks
the
path through
the stub
filters
19
and 20
.
4.72
A
change
of logic
state
on
the
5
octave
line will
reverse the
above
arrangements, causing
D2
to
be
forward biased
and
D1
reversed,
thus inserting
the
filter
formed
by
stubs 19
and
20 with C9,
CIO
and
Cl
1
.
The
filter
outputs are fed via
D5
and
D
6
to
the
common
output
via the
combiner diode D7.
Range 4
Division
and
Filtering
4.73
The Range 4
divider IC3
is
fed from
Q2
and
the
divided
signal drives the
Range
1
mixer
via
Q10
and
the
Range
3 divider IC2
via
Q9.
The Range 4
filter
is
fed
via
Q9
and
Q10,
which
drive the input transformer
T3
in
antiphase.
Range
switching
is
obtained by
biasing the diodes
D18 and D19
via the
range
line
RG.
4.74
When
Range 4
is
selected a
positive
voltage forward
biases
D18 and
D
8
,
and
reverse biases
D19,
allowing the
signal
to
pass
through
the
filter
formed
by
stubs
15
and
16,
with
C42,
C43
and C46.
When
the
^
octave
level (pin
8
)
is
high
it
will
apply forward
bias
to
D21,
thus
connecting
C44
which
extends
the
filter
pass
band
to
a
lower
frequency.
The
r.f.
output
signal
is
fed via
D
8
to
the
common
output
line
via the
combiner
diode D7.
Range
3
Division
and
Filtering
4.75
The Range
3 divider
is
IC2
which
feeds the
Range
2 divider via
Q
1
1
and
the
Range
3
filter
from
Q12
collector via
diode D23,
which
is
forward biased
by
the
positive logic
from the range
selection.
The
filter
is
a conventional
LC
network
with
an
extension of
the
lower passband
whenever D26
is
forward biased by the
2
octave
logic, thus
inserting
C58
in
parallel
with
C59.
The
output
is
fed via
D9
to
the
common
line at
the
combiner diode D7.
Range
2
Division
and
Filtering
4.76
The Range
2 divider
is
1C lb
which
feeds the
Range
2
filter
from 1C
lb/1 5.
The
Q
output from
IClb/14
is
fed
to
another
divider (ICla)
which
provides a
16
to
32MHz
signal
to
the
Display
Counter Assembly
.
4.77
The Range
2
filter
is
similar
to
that
of
Range
3.
A
positive
range
signal
forward
biases
D27
and
DIO and
allows the
r.f.
signal to pass
through the
filter.
The
lower passband
is
extended
when
^
octave
logic
forward
biases
D30,
thus inserting
C70
in
parallel
with
C71
.
9081
&
9082 Vol
.2
4-12
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