HP 8340B Manual page 133

5-3. 100 MHz VOLTAGE-CONTROLLED CRYSTAL OSCILLATOR (VCXO),
A30 (Cont'd)
6. Disconnect cable W35 from A30J2 100 MHz OUT. Connect Spectrum Analyzer RF Input to A30J2.
7. Adjust A3004 100 MHz ADJ through its full range while monitoring frequency indication on Spec-
trum Analyzer. Adjustment should provide a minimum adjustment range of plus and minus 300 Hz
centered about 100 MHz. If adjustment does not provide sufficient range, select new values for
factory selected components A30C8 and A30L4. A30L4 is used to center the adjustment about
100 MHz and A30C8 is used to adjust the range of A30C4. Refer to Table 5-2 for range of values.
Refer to Table 5-4 for HP Part Numbers.
8. Adjust A3004 100 MHz ADJ for Spectrum Analyzer indication of 100.0000 MHz
9. Disconnect cable A3OW1 at A31J1 400 MHz IN and connect the open end of this cable (A30Wi) to
the Spectrum Analyzer input using a BNC to SMB Snap-on test cable and SMB male-to-male
adapter. Set Spectrum Analyzer controls to view a 400 MHz signal.
10. The 400 MHz output should be —10 dBm ±3 dB.
11. Adjust the DC power supply for OV at A3OTP1 (TUNE). Connect Spectrum Analyzer to A30J2.
Adjust Spectrum Analyzer to view 100 MHz.
12. Frequency indication on Spectrum Analyzer should be less than 100 MHz. If not, repeat Steps 2
through 7.
13. Set power supply for an output of —25 Vdc. Verify TUNE test point A3OTP1 is at —25 Vdc.
14. Frequency indication on Spectrum Analyzer should be greater than 100 MHz. If not, repeat Steps
2 through 7 and verify that the oscillator's range is 100 MHz ±300 Hz. Disconnect power supply
from A3OTP1. Reconnect 10 MHz signal cable from Spectrum Analyzer to the OUT's rear-panel
EXT FREQUENCY STANDARD.
400 MHz OUTPUT ADJUSTMENT
15. Set Spectrum Analyzer to 500 MHz center frequency and 100 MHz frequency span per division.
16. Connect Spectrum Analyzer to A3OW1 cable. Adjust A30C3, A3002, and A3OC1 400 MHz adjust-
ments, in that order, to maximize the 400 MHz signal's output power and minimize all harmonics
of 100 MHz. The 400 MHz signal should be —10 dBm ±3dB and the harmonics at 100, 300, 500,
600, 700, and 900 MHz must be greater than 40 dB down from the 400 MHz signal. Harmonics at
200 MHz must be greater than 25 dB down from the 400 MHz signal. Harmonics at 800 MHz must
be greater than 15 dB down from the 400 MHz signal. It may be necessary to perform the adjust-
ments more than once. This should be done in the order stated each time through the adjust-
ments.
17. The amplitude of the 400 MHz signal should be —10 dBm ±3 dB. This amplitude is set by
selecting attenuator network resistors A30R67, A30R68, and A30R69.
18. If the amplitude of the 400 MHz signal is not within 3 dB of —10 dBm, note the amplitude and
change the values of A30R67, A30R68, and A30R69 as necessary to adjust the amplitude to —10
dBm ±3 dB. Table 5-5 contains a list of attenuations in 1 dB steps and the corresponding values
for the attenuator network resistors to adjust the level to —10 dBm. Refer to Figure 5-6 for
location of resistors.
HP 8340B/41B
0.0001 MHz.
±
Adjustments 5-21