Chapter 2 143
Adjustment Procedures: HP 3335A Source not Available
5a. DC Log Amplifier Adjustments
A4 Log Fidelity Adjustment
This adjustment consists of adjusting A4R531 until the error is
adjusted to zero.
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 RFΩ output to the spectrum analyzer 50Ω
input. Press
LINE to turn the spectrum analyzer on.
3. On the spectrum analyzer, press
PRESET, CAL, IF ADJ OFF, and ADJ
CURR IF STATE.
4. Set the spectrum analyzer controls as follows:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0
Resolution BW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 kHz
Reference level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −10 dBm
5. Set up an HP E4421B as follows:
Frequency. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 MHz
Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −10 dBm
6. On the spectrum analyzer, press
MKR and MARKER DELTA, then
decrease the source power to −26 dBm.
7. Calculate the error. The error = Delta Marker reading + 16 (in dB).
8. Set the source power to −10 dBm.
9. Adjust A4R531 (see Figure 2a-4) to read 2 times the error, press
CAL
and ADJ CURR IF STATE.
10.Repeat to check. Readjust as necessary to get error adjusted to zero.
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