HP 8340B Manual page 144

5-5. 20/30 LOOP PHASE LOCK, A36, A38, A39, A40, AND A43 (Cont'd)
49. Connect the Function Generator to A36TP3. Adjust the Function Generator amplitude to place the
20 kHz signal displayed on the Spectrum Analyzer at the 0 dBm reference line.
Set the Function Generator to 50 kHz.
50.
51. Set the Spectrum Analyzer Marker at 50 kHz.
52. Adjust A36L7 and A36L8 (50 kHz NULL) to null the 50 kHz signal displayed on the Spectrum
Analyzer. Refer to Figure 5-12 for location of adjustments.
53. Note the level of the 50kHz signal. This level should be at least 65 dB down from the level of the 20
kHz response. Disconnect the test equipment from the A36 assembly.
Disconnect the active probe from the Spectrum Analyzer and connect the Spectrum Analyzer
54.
input to A36J2 (OUT 200-300 MHz) using a BNC to SMB snap-on test cable. Set the LINE switch
to ON.
55. Set the Spectrum Analyzer as follows:
INSTR PRESET
START FREQ
STOP FREQ
REFLINE
MARKER
56. Connect an external low-voltage dc power supply positive lead to A36TP3 and the negative lead
to any convenient chassis ground. Set the external power supply for ± 16.0 Vdc
57. The Oscillator frequency should be 310 MHz
not, remove the metal shield from A36 and increase or decrease the spacing between turns of
A36L4 and increase or decrease the area of the single turn of A36L5 to properly tune the
oscillator.
58. Change the power supply voltage to +4.0 Vdc ±0.1Vdc.
59. The Oscillator frequency should drop below 200 MHz with an amplitude greater than —7 dBm.
60. Repeat Steps 56 through 59 if necessary to meet requirements.
61. Setthe LINE switch to STANDBY. Reinstall the metal shield on A36 if itwas removed, reinstall A36
(PLL1 VCO) in the instrument, and reconnect all cables.
62. Remove A38 (PLL1 IF) from the instrument and install it on an extender board. Connect all the
cables to A38.
63. Set the LINE switch to ON and press [INSTRPRESET]. Press [CW] then enter [1] [3]
[MHzI.
HP 8340B/41B
10 MHz as
indicated on the Spectrum Analyzer. If
±
Press
150 MHz
470 MHz
+lOdBm
PEAK SEARCH
±0.1 Vdc.
[9] [7]
[.]
Adjustments 5-33