HP 8753E - High;Low Band Transition Adjustment

High/Low Band Transition Adjustment
&x&red Equipment and 9bols
Non-metalhc Adjustment lb01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . HP P/N 8830-0024
Amlgzer warmup time: 30 minutes.
This adjustment centers the VCO (voltage controlled oscillator) of the Al2
reference assembly for high and low band operations.
3. Press m ~~~~~~~~~~~~~~ (--& a (.., Illl @-&
4. Press (Scale L.1] Lxl_] and observe the VCO tuning trace:
n If the left half of trace = 0 flOO0 mV and right half of trace = 100 to
200 mV higher (one to two divisions, see Figure 3-20): no adjustment is
necessary.
n If the adjustment is necessary, follow these steps:
a. Adjust the VCO tune (see Pigure 3-21) to position the left half of the
trace to 0 f125 mV. The variable capacitor, C85, has a half-turn tuning
range if the Al2 Reference Board is part number 08753-60209, and
seven turns if the part number is 08753-60357. Be careful not to
overtighten and damage the seven-turn capacitor.
b. Adjust the HBLB (see Figure 3-21) to position the right half of the trace
125 to 175 mV (about 1 to 1.5 divisions) higher than the left half.
n Refer to Chapter 7, “Source Troubleshooting,” if you cannot perform the
adjustment.
3-52 Adjustments and Correction Constants