Operation
0
•
•
•
0
NOTE
Amplifier
is
not
calibrated when using
external mixer.
Set INPUT ATTENUATION to 20 dB*. Connect
cable supplied with waveguide mixer to EXT
MIXER input.
~~~~~]
Discharge cable
to
avoid damage
to
mixer
diode. Touch edge
of
male
BNC
connec.
tor
on cable to edge
of
female
BNC
con-
nector on mixer
to
discharge cable. See
11517 A Operating Note.
Connect cable to mixer. The LO signal from the
RF Section and the mixing products
to
the
RF
Section are carried
in
this cable.
Connect appropriate waveguide adapter to the
mixer.
Connect waveguide adapter
to
signal source.
For
linear operation, adjust signal source for
output
no
greater than
.03 milliwatt.
For
minimum inter-
modulation and spurious signals, keep input signal
level
at
-30 dBm
or
below.
Set Frequency Band Switch
to
lowest
BAND
which covers range
of
signal under investigation.
(External mixer bands are
as
follows: n=6- 10.25
- 22.55 GHz;
n~6+
14.35 - 26.65 GHz;
n~10-
18.45 - 38.95
GHz
and
n~10+
22.55 - 43.05
GHz.)
When
other bands are selected the external
mixer circuit path
is
opened
by
coaxial switches in
the
RF Section.
Set
Analyzer controls
as
follows:
POWER
..............................
ON
BAND
..........................
See step 5
FINE
TUNE
......................
Centered
0
•
Model8555A
~··~··-~-
..
-~!
lf----b:J-~-1
SIGNAL
UNGER
INVESTIGATION
BANDWIDTH
.....................
300kHz
SCAN WIDTH
.......................
FULL
SCAN
WIDTH PER DIVISION
........
10
MHz
TUNING STABILIZER
..................
ON
SIGNAL IDENTIFIER
.................
OFF
BASE LINE CLIPPER
.............
12
o'clock
SCAN TIME PER DIVISION
.....
0.2 SECONDS
LOG
REF
LEVEL
.....................
0
dB
LOG
REF
LEVEL Vernier
..............
CCW
VIDEO FILTER
......................
OFF
SCAN TRIGGER
....................
AUTO
SCAN MODE
.........................
!NT
{Input
attenuator
IS
not
in
external
mixing
circuit,
but
switch
controls
position
of
LOG
REF
LEVEL
index
lamps
and
attenuator
provides
termination
for
internal
mixer
input
port
to
decrease
crosstalk.)
Adjust Display Section for a convenient display .
(WRITING SPEED-STD, PERSISTENCE-MIN,
INTENSITY-dpproximately 12 o'clock.)
Adjust FREQUENCY control
to
position marker
under signal
of
interest.
Set SCAN WIDTH
to
PER DIVISION and adjust
FREQUENCY control
to
center signal
on
display.
Adjust
LOG
REF
LEVEL for a convenient signal-
to-noise ratio.
Adjust
EXT MIXER
BIAS
for best signal trace.
Adjust BANDWIDTH,
SCAN
WIDTH
PER DI-
VISION
and SCAN TIME PER DIVISION
to
obtain best detail in region
of
interest.
Readjust
EXT MIXER BIAS for maximum ampli-
tude.
Figure
3-6.
External
Mixer
(HP
11517A)
Operating
instructions
3-16
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