HP 5254C - MULTIPLIER AMPLIFIER ALIGNMENT

Section
V
Model
5254C
e.
Remove
the
four
screws
that
secure
the
mixing
frequency
dial
and
remove
dial.
f.
Remove
the
two
screws
that
secure
front
panel
to
bottom
plate
(MP8).
g.
Cut
connecting
wires
at
meter
terminals.
h.
Remove
panel
from
instrument
to
permit
access
to
meter.
i.
Remove
the
two
screws
from
meter
bezel
at
sides
of
meter.
Push
bezel
forward
as
far
as
possible.
j.
Grasp
meter
and
gently
pull
(with
bracket
MP5)
backwards
out
of
front
panel
hole.
k.
Remove
meter
bracket
(MP5)
and
hardware
from
meter
and
install
in
identical
manner
on
replacement
meter.
l.
Replace
meter
(with
bracket)
in
unit by
reversing
procedure
used
in
steps
a
through
k.
Strip
1/4
inch
insulation
from
ends
of
each
connecting
wire
and
solder
to
meter
terminals.
White
wire
goes
to
inside
term-
inal;
black
wire
goes
to
outside
terminal.
5-36.
CIRCUIT
ADJUSTMENTS.
5-37.
MULTIPLIER
AMPLIFIER
ALIGNMENT
PRO-
CEDURE.
Two
procedures
are
given
for
multiplier
amplifier
alignment;
Procedure
a is
to
be
used
if
the
multiplier
is
working
and
just
requires
peaking,
and
Procedure
b
if
the
multiplier
has
no
output
(checkout-
put
by
measuring
dc
voltage
at
junction
of
C25
and
R16;
normal
reading
is
2
volts
or
more).
a.
1)
With
counter
power
off,
connect
converter
to
counter
with
Extension
Cable
HP
10506
B.
2)
Remove
four
screws
which
secure
MP6
(top
plate)
and
remove
MP6.
3)
Set
UHF
Signal
Generator
to
any
frequency
between 2 and
3
GHz at
50
mV
and
connect
to
converter
INPUT.
4)
Turn
counter
power
on
and
set
controls
as
shown
in
Figure
3-1.
Tune
converter
for
a
maximum
indication
on
Level
Indicator
Meter.
5)
Adjust
UHF
Signal
Generator
output
level
for
a
reading
on
the
red/
green
line
of
the
con-
verter
Level
Indicator
Meter.
NOTE:
If
counter
displays
a
difference
fre-
quency
below 1
MHz,
adjust
UHF
Signal
slightly
so
counter
display
is
between
1
to
50
MHz.
6)
Adjust
A1L2,
A1L3,
A1L5,
A1L6,
A1L8,
A1L10
and
A1C25
for a
maximum
indication
on
Level
Indicator
Meter.
NOTE :
If
the
Level
Indicator
Meter
reading
increases
to
above 1/2
of
full
scale,
readjust
the
UHF
Signal
Generator
to
keep
indication
near
the
red/'
green
line.
7)
Potentiometer
A1R17
needs
no
adjusting
pro-
viding
input
sensitivity
is
between
25
mV
and
50
mV
throughout
the
input
frequency
range.
8)
Replace
MP6
(top
plate).
b.
1)
With
counter
power
off,
connect
converter
to
counter
with
Extension
Cable
HP
10506B.
2)
Remove
four
screws
which
secure
MP6
(top
plate)
and
remove
MP6.
3)
Turn
counter
power
on.
4)
Connect
HP
140A
with
HP 14 10
A plug
in
(1000
MHz
Oscilloscope),
using
an
HP
10214A
Divider
and
an
HP
102
17A
Blocking
Capacitoi
to
collector
of
A1Q1.
Set
Oscilloscope
vert-
ical
gain
for
5V/cm(with
10:1
Divider
set
to
.
5
V/cm)
and
horizontal
to .
05
/is/
cm,
and
trigger
oscilloscope
from
counter
OUTPUT
STD
FREQ
10
MHz
(rear
of
counter).
5)
Observe
waveform
and
tune
A1L2
for
maxi-
mum.
Waveform
and
amplitude
should
ap-
proximate
that
in
test
point
2,
Table
8-1.
6)
Connect
oscilloscope
probe
to
the
collector
of
A1Q2.
Set
oscilloscope
Vertical
to
2
V/cm.
7)
Observe
waveform
and
adjust
A1
L3 for
maxi-
mum
;
then
adjust
A1L5
for
maximum.
Wave-
form
and
amplitude
should
approximate
that
in
test
point
3,
Table
8-1.
8)
Connect
oscilloscope
probe
to
collector
of
A1Q3.
9)
Observe
waveform
and
adjust
A1L6
for
the
approximate
waveform
and
amplitude
shown
in
test
point
4,
Table
8-1.
10)
Connect
oscilloscope
probe
to
collector
of
A1Q4.
Set
oscilloscope
Vertical
to
1
V/cm.
11)
Observe
waveform
and
adjust
A1L8
for
max-
imum.
Waveform
and
amplitude
should
ap-
proximate
that
shown
in
test
point
5,
Table
8
-
1 .
12)
Connect
oscilloscope
probe
to
collector
of
A1Q5.
Set
oscilloscope
Vertical
to
2
V/cm.
13)
Observe
waveform
and
adjust
A1 LI
0 for
max-
imum.
Waveform
and
amplitude
should
ap-
proximate
that
shown
in test
point
6,
Table
8
-
1 .
14)
Connect
oscilloscope
probe
to
collector
of
A1Q6.
Set
oscilloscope
Vertical
to
10V/cm.
15)
Observe
waveform
and
tune
A1C25
for
max-
imum.
Note
two
maxima
should
be
noted
as
the
capacitor
is
turned
through
360°. Wave-
form
and
amplitude
should
now
approximate
that
in test
point
7,
Table
8-1.
The
output
should
be
a
sine
wave
of
50
Me,
approximately
20
volts
amplitude;
if
not
proceed
to
steps
16
through
19 and
then
repeat
step
15.
16)
Adjust
capacitor
A1C25
to
the
centei
of
its
range
(notch
perpendicular
to
axis
of
leads).
17)
Unsolder
from
the
board
the
end
of
A1L12
at
its
junction
with
A1L11
and
A1C23.
18)
Observe
the
waveform
and
tune
A1L12
for
a
maximum
by
increasing
or
reducing
the
loop
diameter.
Resolder
A1L12
to
the
board.
19)
See Para.
5-37
a
for
final
peaking
adjustment.
5-4