HP 8591C, Руководство пользователя, Страница: 48 / 373

Channel Measurements
Making Channel Measurements
OEC
1993
37.5
AT
A I R
PEAK
HRCT
I
CENTER 57.888 MHz
RES RT
Figure Channel Tuning Menu
4. with a 50 input:
Use an external 50 to
75 matching block to compensate for the impedance mismatch
between a 75 impedance system and the spectrum analyzer’s 50 input
impedance. If you use an HP 11981A external pad, the external pad
causes approximately 5.8 of amplitude loss. The external pad function
(EXT PAD YES MO can be used to compensate for this amplitude loss.
l
Connect the matching pad to the spectrum analyzer input.
l
Press Analyzer Input EXT PAD YES NO to underline YES.
l
Press Prev Menu to return to the Setup menu.
If you are using a spectrum analyzer with 50 input impedance but are
not using an external matching
block, the analyzer will compensate
for most of the impedance mismatch, but amplitude measurements can
have up to
additional error caused by the uncompensated
mismatch over the frequency range.
C A U T I O N
dc voltages in excess of 25 V and ac power-line voltages in excess of
100 Vpeak can permanently damage the analyzer input.
5.
using
an
An external amplifier may be
required for the carrier-to-noise test. See Chapter 8 for more information
about when a preamplifier is required for the carrier-to-noise test. The
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