9. Frequency Response Adjustment
Procedure
Note
The YIG-tuned filter/mixer slope and offset adjustment must be correct before
the high band part of the frequency response adjustment can be done.
1. Connect the equipment as shown in Figure 2-17. Do not connect the HP 8482A power
sensor to the HP 11667B power splitter.
2. Zero and calibrate the HP
8902A/HP
8482A combination in log mode (power levels read
out in
dBm)
and connect the power sensor through an adapter to the power splitter.
3. Place the WR PROT/WR ENA jumper on the A2 controller assembly in the WR ENA
position. The jumper is on the edge of the A2 board assembly and can be moved without
folding the board down.
4. Press
[PRESET)
on the HP 85623 and set the controls as follows:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OHz
Resolution bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 kHz
dB/division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 dB
5. Press (INSTR PRESET) on the HP
8340A/B
and set the controls as follows:
CWfrequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lO MHz
Powerlevel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -4dBm
6. Set ref level cal DAC to zero. Press
m),
REF LVL ADJ and use the knob to set the value
to 0. Press STORE
REV
LVL
.
7.
On the HP 85623, press
(MKRI,
(CAL), MORE
i
OF 2,
SERVICE
CAL DATA, then
FLATNESS . The current value of the RF Gain DAC should be displayed in the active
function area.
8. Enter the appropriate power sensor calibration factor into the HP 8902A.
9. Set the HP
8340A/B
m
output to the frequency indicated in the active function area of
the HP 85623 display. Adjust the HP
8340A/B
POWER LEVEL for a -10
dBm
reading
on the HP 8902A.
10. On the HP 85623, adjust the RF gain DAC value using the front-panel knob or keypad
until the marker reads -10
dBm
fO.10 dB. Each DAC count results in an amplitude
change of approximately 0.01 dB.
11. On the HP 85623, press
@)
to proceed to the next frequency.
12. Repeat steps 7 through 10 for all low-band frequencies
210
MHz.
13. Press
m
until 10 MHz is displayed in the active function block. Record the RF gain DAC
value at 10 MHz.
10 MHz RF gain
DAC valueAdjustment Procedures 2-45