If Bandpass Adjustment; If Bandpass Adjustment Setup - HP 8562E Service Manual

3. IF Bandpass Adjustment

A5 IF assembly
Resolution bandwidth accuracy and selectivity
The center frequency of each IF bandpass filter pole is adjusted by DAC-controlled varactor
diodes and an inductor (for the LC poles) or a transformer (for the crystal poles). The
inductors and transformers are for coarse tuning and the varactors are for fine tuning by the
microprocessor. The inductors and transformers are adjusted such that the varactor diodes
are biased near the middle of their capacitance range. The varactor diode bias is measured
with the DVM.
This procedure is not a routine adjustment. It should be performed only
if repairs to the A5 IF assembly are made. If the entire A5 IF assembly is
replaced, the assembly arrives pre-adjusted from the factory and requires no
further adjustment.
SPECTRUM
ANALYZER
Digital voltmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Special tuning tool (for slot-type tuning slugs) . . . . . . . . . . . . . . . . . . . . . . . 8710-1010
Special tuning tool (for fork-type tuning slugs) . . . . . . . . . . . . . . . . . . . . . . . 8710-0772
5
A3
Figure 2-5. IF Bandpass Adjustment Setup
3. IF Bandpass Adjustment
DIGITAL VOLTMETER
HP 3456A
HP 34118A
Adjustment Procedures 2-21
I
S K 1 5