Vdc Reference Voltage - HP 3336A Operating Manual

Adjustments Model 3336A/B/C
f. Program the 3336 to 20 MHz and set the log ref level on the spectrum analyzer to — 30 dB.
g. Switch the spectrum analyzer to manual scan mode and move the beam to the 10 MHz
spur in the center of the screen, then switch to non-storage.
h. Turn on PHASE entry with MODIFY at 1° on the 3336.
i. Adjust the phase through 360° and find the worst case spur.
j. Adjust A3R115 to minimize the worst case spur. Adjust the phase through a full 360°
again and make sure that the worst case is <50 dB on the screen (<70 dB below the signal).
5-21. —10.2 Vdc Reference Voltage Adjustment.
5-22. This procedure sets the dc reference voltage used in the DAC and the leveling loop.
ese spbro-
(sf
Required Equipment:
de voltmeter -hp- Model 3455A @
a. Connect the dc voltmeter to test point A4TP208.
b. Adjust A4R269 until the dc voltage at test point A4TP208 is —10.202V, +.001V.
5-23. Digital-to-Analog Converter (DAC) Offset Voltage Adjustment
ae Ao
5-24. This adjustment compensates for the offset voltage in the DAC.
Required Equipment:
dc voltmeter -hp- Model 3455A
a. Connect the dc voltmeter to test point A4TP AMPL.
b. Set the output amplitude to maximum (+8.76dBm, 50 ohm output or +7.00 dBm,
75 ohm output). -
OFFSEI
c. Adjust A4R40 (located between A4J4 and A4J9 — labeled DAC @8) until the de voltmeter
reads +10.000V, +1mV.
5-25 Leveling Loop Amplifier Zero Adjustment.
5-26. This adjustment compensates for the voltage offsets of the leveling loop amplifier.
Required equipment:
oscilloscope -hp- Model 1740A &
5-8