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5. DC Log Amplifier Adjustments
11. Repeat steps 5 through 10.
A4
LOG
Fidelity
Adjustment
1. Press (LINE) to turn the spectrum analyzer off. Remove the spectrum analyzer cover and
place the spectrum analyzer in the service position as illustrated in Figure 2-9.
See Figure 2-10 for adjustment location.
2. Connect the HP 3335 50
0
output to the spectrum analyzer 50
fl
input. Press (LINE) to
turn the spectrum analyzer on.
3.
Press
(-),a,
IF
AlI>
ON OFF
(OFF),
AD3
CURR
IF STATE.
4. Set the spectrum analyzer controls as follows:
Center frequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...15 MHz
Span
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..O
Resolution bandwidth
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 kHz
Reference level
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10
dBm
5. Set up an HP 3335A as follows:
Frequency
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
..15MHz
Amplitude
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10
dBm
6. ,Press
(MKR),
MARKER DELTA on the spectrum analyzer.
7. Decrease the HP 3335A power to -26
dBm.
8. Calculate the error:
Error = delta marker reading
-
16 dB
9. If the error is less than f0.2 dB, no adjustment is necessary.
10. Set the HP 3335A power to -10
dBm.
11. Adjust A4R531 (
see Figure 2-10) to read two times the error. For example, if the
calculated error is
+0.75
dB,
adjust A4R531 for a delta marker amplitude reading of
t1.5
dB.
Press (CAL),
ALU
CUEE
IF STATE .
12. Repeat steps 7 through 11.
Adjustment Procedures 2-33