HP 3575A - 5-47. High Frequency Log Amplifier Adjustment

Nlodel
3575A
the termifiqtions must be
ol
equal
leugth
and
should be as
short as
possible.
b. Set the 35754 controls
as
fouows:
DISPLAY*
...,
.
. ..PHASE
Voltage
Range . 0.2
mV
"
2
V
(both
channels)
FREQUENCY
RANGE .
1 kHz-13 MHz
PIIASE REFERENCE ..
, ... ....
... A
*
Options
001 003: Set
the AMPLI-
TUDE
B/PHASE switch
to
PHASE.
c. Set the
Frequency Synthesizq
amplitude
to
+
25.05
dBm and
frequency to 12.99
Mllz.
d.
Set
Al R4
(PHASE
ADJ)
fu1ly
clockwise.
e.
Set A2R4
(PHASE
ADJ)
fully counter-clockwise.
[. Obscrve
the ]575A
phase
readiog.
g.
Adjust
A2R4
(PHASE ADJ) until the
phase reading is
approxinately
1/2
the
value
observed on Step
f.
h. Adjust AlR4
(PHASE
ADJ)
for a
phase reading
of
00.0
degrees.
i. Reverse
the A and
B input connections
and allow
l0
seconds
for
the
phase reading
to
stabiliz
e.
j.
Note the
phase reading:
-degrees.
If the
phase
reading is
geater
than
:r
I degree,
perform
Steps
k
tfuough
o, if not;proceed
to Step
p.
k.
Adjust
A2R4
(PHASE
ADJ)
until
the
phase
reading
is
3/4 the value
noted in Step
j.
l. Adjust
AlR4
(PllASE
ADJ)
until the
phasc
reading
is
1/2 thc
value noted
in Step
j.
m. Note the
phase
reading:
degrees.
Again
revcrse
the A and
B input connections
and
allow 10
seconds for the
phase
reading
to stabilize.
n. The
abs;lutc
value ol the
phase
reading should be
within
1
0.5 degrees
of the valtL€ noted
in Step tn. If it is
not.
split
the diflcrence by adjusling
AlR,1.
o.
Repeat
Steps
m and
n until the absolutc
valucs
ol
the
two
readings are cqual within
10.5
degrees.
p. Note
the
phase
readingr degrees.
Sct the
PHASE
REFERENCE switch
to the
-A
positon
and
alkrw l0
seconds for the
phase
rcading to stabilize.
q.
Again
oote the
phase reading:
-
degees.
ADJUSTMENT
PBOCEDUBES
Section V
r. T\e
difference
bctween the
readings
noted in
Steps
p
and
q
should
be t80 degrces
t
0.5
degrees. lf it is
not,
split
the
error between the
A and
-
A reference
settings
by
adjusting
AlR4. For
example, if the
A reading is
+
1.0
degree and the
-
A rcading is
-
179.6 degrees,
the
error is
0.6
degrees
and At R4 should
be adjusted
so the ' A
reading is
-
179.3 and the A
reading is
+
1.3.
5.47.
High
Frequency Log
Amplifier
Adiustment.
548. This adjustnlent
controls
the high liequency
response
of the log
arnp. See
note following
Step
m.
RECOMMENDED
TEST
EQUIPMENT
:
Frecluency
Synthesizer
(-hp-
Model
3320B)
(2)
50-ohm
Fecd-Thru
Terminations
(-hp-Model
I10,18C)
Power Splitter
(See
Figure 5-l)
22
pin
PC Board
Extender
(ip'Part No.
5060'5989)
a. Rernove the screws
front the
A3 and A4
assemblies
and
put
the 43
assenrbly on the
cxtender.
b. Connect
the 50-ohm
output
of
the Frequency
Synthesizer
to the Power Splitter.
Connect
the
outputs of
the
Power Spiitter, terminated
in 50'ohm
loads, to
the
3575A inputs.
NOTE
Connect
the 50<thm
Feed'Thru Temtinations
directb,
to the 3575A
inputs.
The cables
Jiom
the
Po\rer Splitter to
the ternxinations
must be
of equal
length and
shoud be as
short as
Possible.
c. Set
the 3575A
controls
as follows:
DISPLAY*.
..
.PHASE
VoltageRange
.....0.2rnV-2V
(both
channelsJ
FREQUENCYRANGE
....
.
1
kllz'13MHz
PHASEREFERENCE
...,.....,.....
A
d. Set\
the
Frequency Synthesizer
amplitude
to
+
25.05 dBm and
frequerrcy to
12.99 MHz.
e. Set the
AMPLITUDE FUNCTION
to A.
l. Adjust 43Ll ior a
lelt
panel
rleter
reading of 5.5 to
5.7
.
g.
Remove the
A3
assembly
front thc extender
and
install in ilst
rument.
h. Put the A4 assemblv
on the extender.
*Options
OOl OO3:
Set the AMPLITUDE B/PHASE
switch
to PHASE.
5,1
3