HP 8340B Manual page 304

5-16.
LEVELED RF OUTPUT ADJUSTMENTS (Cont'd)
14.
On the DUT, press
[CW] [1] [7] [.]
[5] [GHz]. Adjust
A24R8 (X3C)
for
a
MOD LEVEL trace
as
described
in
step
13.
If
the
DUT
is
an
HP 8341 B, proceed with step 16.
15.
On the
DUT, press
[CW] [2] [3] [.] [3] [GHz]
and adjust A24R11 (X4C) for
a
MOD LEVEL trace
as
described in
step
13.
16.
Set the
oscilloscope to
DISPLAY
A and set CHAN A
to 0.02
V/Div.
17.
Press
[RECALL] [2]
on
the DUT. The
oscilloscope display should be similar to Figure
5-54. Adjust
A24R12 (MIN)
so that
all
points on the trace
are reduced
to the lowest possible voltage level (i.e.,
maximum negative voltage).
18.
On the DUT, press [RECALL] [1] [CW] [7] [GHz].
Set the oscilloscope for DISPLAY CHOP, CHAN
A
to 0.5 V/Div, and
CHAN B
to 0.5 V/Div.
19. Using the DUT's
[«•] and [•»] step keys, step through Band
2
from
7
to 13.4 GHz
and check for
an optimum SRD
bias
trace
(Figure 5-55,
Waveform
A, B,
and
C)
at each
step.
If
not optimum,
adjust A24R1 (OFF A)
if
the frequency
is closer
to 7 GHz, or adjust A24R2 (OFF B) if
the
DUT
frequency
is
closer
to 13.5 GHz.
If
an adjustment is made, step through the entire band again,
making sure every step
is optimized or acceptable
if all
the steps cannot be optimized.
20. Using the DUT's [*]
and
[^]
step keys, step
through Band 2
from
7
to 13.4
GHz
and readjust
A24R5 (X2C)
if
necessary
to
improve the
MOD LEVEL
trace. Also, adjust A24R1 (OFF A) and
A24R2 (OFF B)
if
necessary
to optimize the
SRD
Bias as in
step
19
above.
If
any adjustments are
made, step through Band
2
again
until the
SRD
bias and the
MOD LEVEL
trace
is
optimized.
It
will
not be possible to adjust the MOD LEVEL trace for optimum
at each step, so adjust for best
compromise trace across Band
2
(see Figure 5-55, Waveforms
D
and
E).
NOTE
The SRD bias trace
is adjusted
in
Band
2 with A24R1 (OFF A) and A24R2
(OFF B) set for optimum.
It
should not require any other adjustments in
Bands
3
or 4, unless the SRD bias
trace
is
bad
as shown
in Figure 5-55.
If
either the
OFF A
or
OFF B
controls are adjusted in Bands
3
or 4,
then
each
band will
have
to be
rechecked,
starting with Band
2
at
7
GHz and
stepping through each band.
21.
On the DUT, press
[CW] [1] [3] [.] [5] [GHz].
Using the DUT's [^]
and
[^]
step keys, step
through Band
3
from 13.5
to 19.9 GHz and readjust
A24R8 (X3C)
if
necessary to achieve the best
MOD LEVEL trace across Band
3.
If
the
DUT
is
an HP
8341B, proceed to the LINEAR MODULATOR ALC LOOP GAIN
ADJUSTMENTS.
22. On the DUT, press
[CW] [2] [0] [.] [1] [GHz]. Using the
DUT's
step keys, step through Band
4
from 20.1
to 26.5 GHz and
readjust A24R11
(X4C)
if
necessary for the best
MOD
LEVEL trace
across Band
4.
5-106
Adiustmente
HP 8340B/41B