
6. Video Processor Adjustments
6. Video Processor
Adjustments
Reference
Related Performance
Description
IF-Display Section
1 Video Processor
Log Scale Switching Uncertainty Test
The CAL OUTPUT signal is connected to the RF INPUT through a
step attenuator. The instrument is placed in zero frequency span to
produce a dc level output from the log amplifier. The
ZERO
adjustment, which sets the dc offset of the output buffer amplifier of
the log board, is checked and adjusted if necessary. The dc level into
the video processor is adjusted by varying the input signal level and
reference level. The offsets and gains
on
the
Video Processor
are adjusted for proper levels using a DVM.
Equipment
Note
Procedure
S T E P A T T E N U A T O R
D I G I T A L V O L T M T E R
Figure 3-35. Video Processor Adjustments Setup
Digital Voltmeter (DVM) . . . . . . . . . . . . . . . . . . . . . . . . HP
10
Step Attenuator . . . . . . . . . . . . . . . . . . . . . . . . . . HP
The voltage at
may drift noticeably with temperature
during this adjustment. Allow
(Video Processor) to warm up at
least one-half hour prior to adjustment.
1.
2.
3.
4.
5.
Position instrument upright as shown in Figure 3-35. Remove the
top cover.
Set LINE switch to ON and press
PRESET
).
Connect DVM to
and DVM ground to the IF casting.
Connect CAL OUTPUT to RF INPUT through 10
step
attenuator.
Key in
[
CENTER FREQUENCY
)
20 MHz and
[
FREQUENCY SPAN
)
0 Hz.
Press LIN pushbutton.
Adjustments 3-69
Содержание 8568B
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