HP 8340B Manual page 278

5-14.
UNLEVELED RF
OUTPUT ADJUSTMENTS (Cont'd)
If the output
power
begins to
decrease
while adjusting one of these potentiometers (pots)
clock¬
wise
(i.e.,
power
reversal, squegging), adjust the pot counter-clockwise
until the power is peaked
again and then continue turning the pot counter-clockwise until the power
is
reduced
ss
0.5 dB.
It may be desirable to optimize the
power
in one half of the band (maximum power with
no
squegging), even though squegging
is
induced in
the other half. One would do this
if
the side being
adjusted
is
significantly lower in
power
than the other
half.
Once the power is optimized, adjust the
bias in
the other half (using
the pot for that half) to eliminate squegging. Iterate between the two
adjustments to optimize the
power
and to
ensure
that there is
no squegging
in either
half.
19.
Adjust A28R99 (BP1)
to peak the
power
in
the second half of the display.
20. Access Cal Constant 73 by pressing [SHIFT]
[GHz] [7] [3] [Hz] [SHIFT] [ENTRY OFF]
on
the
DUT.
Using the DUT's rotary knob, adjust Cal Constant 73 to peak the power across
the
entire
band (adjust above and below 1024). Repeat steps 19
and 20.
21.
Repeat step
18.
22. Note the position of the minimum power point on the scope. On the DUT, press [MANUAL]. Adjust
the DUT's rotary knob
until
the dot on the scope is
near
the position noted as
the minimum power
point. Slowly vary the position of the dot around this point while observing the
DUT's POWER
dBm display. The minimum power displayed should be
>
1 dB above the
maximum leveled power
specification for the DUT
in
Band 3 (13.35 to 20 GHz). If this is
not
the case, disconnect the
detector from the
DUT
and connect the power meter and power sensor. Again, slowly vary the
rotary knob and determine the power
level
of the minimum power
point.
If it is still
<
1 dB above
the maximum leveled
power specification, press
[CONT]
on the
DUT
and repeat steps
17
through
22.
Band 4
Adjustments (HP
8340B Only)
If
adjusting an
HP 8341 B, proceed to step 31.
23. On the DUT, press
[START FREQ] [1] [9]
[.]
[8] [GHz]
[STOP FREQ] [2] [6] [.] [5] [GHz]
[CONT]
[SAVE][1]
Adjust the scope's vertical position
and/or
sensitivity to display the swept RF output.
24. Adjust
A28R24 (BP2
FREQ)
to
peak
the power across the band.
If this
adjustment has no effect or
reduces the power, return
A28R24
to
full
clockwise and proceed immediately to step 26 (step 25
will
not be required).
25. Adjust A28R25
(BP3 FREQ) to peak the power
in the second
half of the
display.
If A28R25
has
no
effect or reduces the power, return the pot to
full clockwise. Adjust A28R27 (BP2)
to peak the
power across the band.
If
A28R25 (BP3 FREQ) was adjusted from
full
clockwise, adjust A28R28
(BP3)
to optimize
the
power
in
the second half
of the display.
26.
If
the trace goes off the
oscilloscope display in
the following adjustments, adjust
the vertical
position and/or sensitivity controls to view the entire
trace
on the display.
Adjust
A24R9
(X4A)
to
optimize the power
in
the first half
of
the display.
HP 8340B/41B
Adjustments 5-79