CIRCUIT DESCRIPTION
Model
2001
Section D. Amplified triggers are routed into the hysteresis
switch independently of the internal routing transistor,
providing additional (redundant) line rate reliability.
4.5
SWEEP DRIVE (MODULE M2H)
The M2H module provides the correct sweep drive voltage
required by each oscillator as programmed by the Front
Panel Tuning controls, Sweep Width controls, and the Mode
switch.
These programs are summed to a standard voltage level and
then feed shaping circuits for each band which are en-
abled by the B-I and
6-2 voltages and by a synthezied 8-3
voltage.
The shaping diodes conduct at levels determined by a resis-
tor network driven by a constant current source,
07.
Aseach
diode conducts, an additional current is fed into the
summing junction of the output amplifier consisting of
Q12,
013, and Q14.
The output waveform amplitude is controlled by R72, R76,
and
R80 which are connected by switch transistors Q15,
Q16, and Q17 into the feedback path to the summing junc-
tion.
This module also provides two regulated voltages for use
primarily as programming voltages and an inverting ampli-
fier to furnish an inverted triangle wave for use in the
start-
stop mode of programming.
4.6
SWEEP OSCI LLATOR, BAND
1
(MODULE M9H)
The RF sweep signal for band 1 is developed by the hetro-
dyne method which utilizes two UHF sweep oscillators, a
diode mixer, and a wide-band RF amplifier.
Sweep oscillator, Q2, sweeps from approximately 1.4 to
1.65
GHz. The average frequency is adjusted by R2 which
controls the average bias on the varactor diodes,
CRI, CR2,
and
CR3. The sweep drive voltage from pin
9
of the module
is
connected to the opposite side of these diodes causing
the frequency to vary above and below this average fre-
quency in a low-to-high frequency direction.
Sweep oscillator, Q5, is similar to the
02 circuit, however,
the varactor diodes have been reversed, and the polarity of
the bias voltage supplied by R12, course adjustment, and
R13, CENT FINE adjustment, has been changed. These
changes cause the oscillator frequency to vary from a high
to low frequency.
The approximate output frequency is
1.4 and 1
.I5 GHz. This out of phase sweep technique has
several advantages. First, larger sweep widths are obtainable
and second, the nonlinearity (FREQ versus TIME) of one
oscillator is cancelled by the nonlinearity of the second
oscillator.
R9, which is a linearity adjustment, optimizes
this cancelling process by controlling the sweep drive ratio
between the oscillators.
The two sweep signals are combined in a single balance
diode mixer comprised of
L4, L5, CR8 and CR9. The
resultant, difference frequency, of
0 to 500 MHz, is then
amplified in the wide band amplifier consisting of transis-
tor stages
Q11, Q12, and (313.
Transistor stages 06 and 07 supply the blanking voltage to
the wide band amplifier and causes it to be shut off during
the sweep retrace time. The output from the wide band
amplifier is connected to
J1, which in turn is connected to
the output wide band amplifier located in module
MIOH.
A
second output is also obtained from this amplifier and is
coupled,via R45, to a similar wide band amplifier consisting
of transistor stages
Q14, 015, and Q16.
The output from
this amplifier is connected to J2 which in turn is connected
to the marker generating circuits.
Transistors
08, 09, and 010 provide a -15 volt supply to
operate the sweep oscillators. This improves stability and
provides isolation between the oscillators and the -18 volt
supply.
4.7
OUTPUT AMPLIFIER, BAND
1
(MODULE MIOH)
The MlOH module contains a wide band amplifier, an
electronic attenuator, and a leveler amplifier.
WIDE BAND AMPLIFIER
This amplifier provides 2 stages of RF amplification to in-
crease the RF input level present at
01 by about 40dB.
The frequency response of this amplifier
is
reduced for fre-
quencies near 0.5 MHz or lower and above 500 MHz.
The input amplifier stage consisting of 01, Q2, and
03 is
enabled by the
B+1 switching voltage, and the output stage,
consisting of
04, 05, and 06 by the -20 voltage, when the
Front Panel band switch is in the Band 1 position. The -20
voltage also provides current through R30 and the
RF
out-
CIRCUIT
DESCRIPTION
Section D.
Amplified
triggers are
routed
into
the
hysteresis
switch
independently
of
the internal
routing
transistor,
providing
additional
(redundant) line rate
reliability.
4.5
SWEEP
DRIVE
(MODULE M2H)
The
M2H
module
provides the
correct
sweep
drive
voltage
required
by
each
oscillator
as
programmed
by
the
Front
Panel
Tuning
controls,
Sweep
Width
controls,
and the Mode
switch.
These programs are summed
to
a standard voltage level and
then feed shaping
circuits
for
each band
which
are
en-
abled
by
the
B-1
and B-2 voltages and
by
a synthezied B-3
voltage.
The shaping diodes
conduct
at
levels determ ined
by
a resis-
tor
network
driven
by
a
constant
current
source,
07.
Aseach
diode
conducts,
an
additional
current
is
fed
into
the
summing
junction
of
the
output
amplifier
consisting
of
012,
013,
and
014.
The
output
waveform
amplitude
is
controlled
by
R72,
R76,
and
R80
which
are connected
by
switch transistors
015,
016,
and
017
into
the
feedback
path
to
the summing junc-
tion.
This
module
also provides
two
regulated voltages
for
use
primarily
as
programming
voltages and
an
inverting
ampli-
fier
to
furnish
an
inverted triangle wave
for
use
in the start-
stop
mode
of
programming.
4.6
SWEEP
OSCILLATOR, BAND 1
(MODULE M9H)
The R F sweep signal
for
band 1
is
developed
by
the hetro-
dyne
method
which
utilizes
two
UHF
sweep oscillators, a
diode
mixer,
and a wide-band RF
amplifier.
Sweep
oscillator,
02,
sweeps
from
approx
imately
1.4
to
1.65 GHz.
The
average
frequency
is
adjusted
by
R2
which
controls
the average bias on the varactor diodes, CR
1,
CR2,
and
CR3.
The sweep
drive
voltage
from
pin
9
of
the
module
is
connected
to
the
opposite
side
of
these
diodes
causing
the
frequency
to
vary
above and
below
this
average fre-
quency
in a
low-to-high
frequency
direction.
Sweep oscillator,
05,
is
similar
to
the
02
circuit,
however,
the
varactor
diodes have been reversed, and
the
polarity
of
the bias voltage supplied
by
R 12, course
adjustment,
and
R13,
CENT
FINE
adjustment,
has been changed. These
4-6
Model 2001
changes cause the
oscillator
frequency
to
vary
from
a high
to
low
frequency.
The
approximate
output
frequency
is
1.4 and
1.15
GHz.
Th
is
out
of
phase sweep
technique
has
several advantages.
First,
larger sweep
widths
are obtainable
and second,
the
nonlinearity
(FREO
versus
TIME)
of
one
oscillator
is
cancelled
by
the
nonlinearity
of
the second
oscillator.
R9,
which
is
a
linearity
adjustment,
optimizes
this
cancelling process
by
controlling
the sweep
drive
ratio
between the oscillators.
The
two
sweep signals are
combined
in
a single balance
diode
mixer
comprised
of
L4, L5,
CR8
and CR9.
The
resultant,
difference
frequency,
of
0
to
500
MHz,
is
then
amplified
in
the
wide
band
amplifier
consisting
of
transis-
tor
stages
011,012,
and
013.
Transistor
stages
06
and
07
supply
the
blanking
volfage
to
the
wide
band
amplifier
and causes
it
to
be
shut
off
during
the sweep retrace
time.
The
output
from
the
wide
band
amplifier
is
connected
to
Jl,
which
in
turn
is
connected
to
the
output
wide
band
amplifier
located in
module
M
1OH.
A second
output
is
also
obtained
from
this
amplifier
and
is
coupled, via
R45,
to
a
similar
wide
band
amplifier
consisting
of
transistor stages
014, 015,
and
016.
The
outpu
t
from
this
amplifier
is
connected
to
J2
which
in
turn
is connected
to
the marker generating circuits.
Transistors
08, 09,
and
010
provide
a -15
volt
supply
to
operate the sweep oscillators.
This
improves
stability
and
provides
isolation
between the oscillators and the -18
volt
supply.
4.7 OUTPUT
AMPLIFIER,
BAND 1
(MODULE M10H)
The
M 1
OH
module
contains
a
wide
band
amplifier,
an
electronic
attenuator,
and a leveler
amplifier.
WIDE
BAND
AMPLIFIER
This
amplifier
provides 2 stages
of
R F
amplification
to
in-
crease
the
RF
input
level present at
01
by
about
4OdB.
The
frequency
response
of
this
amplifier
is
reduced
for
fre-
quencies near
0.5
MHz
or
lower
and above
500
MHz.
The
input
amplifier
stage consisting
of
01,02,
and
03
is
enabled
by
the
B+l
switching
voltage, and
the
output
stage,
consisting
of
04,
05,
and
06
by
the -20 voltage,
when
the
Front
Panel band
switch
is
in the Band 1
position.
The -20
voltage also provides
current
through
R30
and
the
RF
out-
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