142 Chapter2
Adjustment Procedures: HP 3335A Source not Available
5a. DC Log Amplifier Adjustments
Procedure
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 2a-3. See Figure 2a-4 for adjustment
location.
2. Connect the HP E4421B RF output to the spectrum analyzer 50Ω
input. Press
LINE to turn the spectrum analyzer on.
3. On the spectrum analyzer, press
PRESET, AMPLITUDE, LINEAR,
MORE 1 of 3, AMPD UNITS, dBm, CAL, and IF ADJ OFF.
4. Set the spectrum analyzer controls as follows:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 MHz
Resolution BW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300 kHz
Reference level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .−10 dBm
5. Set up an HP E4421B as follows:
Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 MHz
Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .−18 dBm
Mod On/Off. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Off
6. On the spectrum analyzer, press
PEAK SEARCH and MARKER DELTA.
7. Reduce the input power by 40 dB, to −58 dBm (use an attenuator or
a source with a good relative amplitude accuracy).
8. If the signal is lower on the screen than expected (delta marker
reads a change of greater than 40 dB, such as −41dB), then adjust
A4R544 (see Figure 2a-4) for an even lower level and press
CAL and
ADJ CURR IF STATE. Allow sufficient time for the spectrum analyzer
to complete the adjustment.
9. If the signal is higher on the screen than expected (delta marker
reads a change of less than 40 dB, such as reads −39 dB), then adjust
A4R544 for an even higher level signal and press
CAL and ADJ CURR
IF STATE. Allow sufficient time for the spectrum analyzer to complete
the adjustment.
10.Repeat the adjustment and adjust current state until the delta
marker reads −40 dB ±2dB.
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