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Model 5254C
Section
V
5-38.
CRYSTAL FILTER ADJUSTMENT.
5-39.
To
adjust the cyrstal
bandpass
filter in
the
Multiplier
Amplifier
Assembly
Al,
proceed
as
follows:
a.
With
counter
power
off,
connect converter
to
counter with
Extension Cable
HP
10506B.
b.
Remove
the
four
screws which secure
MP6
(top
plate)
and
remove MP6.
c.
Remove
the
four
screws which secure
MP7
(left
side plate)
and
remove MP7.
d.
Remove
Cavity Output
Cable
Assembly from
MP14
(Machined Amplifier
Shield).
To
prevent
damage
to
the cable
assembly,
first
remove
the four
screws
that
secure
the
Cavity Plug
Assembly
(MP3)
and
remove
the cavity
plug
and
output cable, then
un-
screw
and
remove
the
other
end
of
the output cable
from
MP14
.
Replace
the cavity
plug
(MP3) and
the
four
screws
that
secure
it
to
the cavity.
e.
Connect a
male
BNC
Plug connector
(HP
Stock
No.
1250-0052)
to
the
end
of
the cavity output cable.
f.
Using
BNC
male
to
Type
N
female adapter
(HP
Stock No. 1250-0077),
connect
the output
cable
from
Harmonic
Selector Cavity
to
the
HP
Spectrum
Analyzer.
g.
Set
Spectrum Analyzer
Controls as
follows:
VERTICAL DISPLAY
IF
BANDWIDTH
.
.
SWEEP
TIME
.
.
.
IF
GAIN
SPECTRUM WIDTH
SYNC
FREQUENCY.
.
.
.
ATTENUATOR
.
.
.
.
SIGNAL IDENTIFIER
LOG
1
kHz
30
ms
per
cm
60
dB
100 kc per
cm
INT
.
.
.2-10
GHz
0
dB
OFF
h.
Turn
counter
power
ON
and turn
Converter Mix-
ing
Frequency
control
to
2.
95
GHz.
Figure
5-1.
Spectrum
Analyzer
Display
c.
Set
608E
Signal
Generator
to
50
MHz
at
30
mV
rms
and connect
to
INPUT
of
converter.
d.
Turn
counter
power
ON
and
adjust
Mixer
Bal-
ance Adjust
A5R3
for
a
minimum
reading on
the level
indicator
meter.
5-41.
LOW
PASS
FILTER ADJUSTMENT.
5-42.
The
Low
Pass
Filter
in
the
Video Amplifier
Assembly A5
consists
of
three resonant
LC
parallel
circuits (see
schematic diagram, Figure
8-6).
These
circuits
are pre -tuned and sealed
at
the factory,
and
should
need no
further adjustment.
The
following
procedure can be used
to
verify
correct operation
of
the
filter
circuits
(A5L1,
A5L2, and A5L3)
and
to
check
the
tuning
of
replacement
circuits.
a.
Remove
circuits
(A5L1,
A5L2,
andA5L3)from
the
Video Amplifier
Assembly
board.
b.
Install clips
on terminals
of
RX
Meter.
Clamp
one
leg
of
the circuit
under
test
with
the clip
from
the
LO
side.
Bring
other leg close
to
but not
touch-
ing
the clip
on HI
side.
i.
Tune Spectrum Analyzer
until
the
converter
sig-
nal
is
found.
j.
Observe
100
kHz
sideband and
adjust capacitor
(A1C13)
for
minimum
side
bands
(see
Figure
5-1).
Side
bands should be 30
dB
below
2.95
GHz
reference.
5-40.
MIXER
BALANCE
ADJUSTMENT.
a.
With
counter
power
off,
connect converter
to
counter with Extension
Cable
HP
10506B.
b.
Remove
the
twelve
screws which
secure
MP12
(amplifier side
plate)
and
remove
.
c.
Depending
on
which
circuit
is
under
test,
the
frequency should be
set to the following:
A5L1
117.
3
MHz
A5L2
71.9
MHz
A5L3
63.2
MHz
d.
Tune
in
instrument
with "Detector tuning adjust-
ments"
and
maximize
response, with
and
C
p
set
to
arbitrary
values.
e.
Set
Rp
to "infinity"
and
Cp
to
zero.
f.
Null the
response
with
the
Zero
Balance
adjust-
ments.
g.
Clamp
the
other
leg
to
the
HI
side
clip.
h.
Leave
Cp
at
zero; alternately tune the
circuit
with tuning
wand
and
adjust
Rp
dial until
a
null
is
obtained.
5-5
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