HP 8591C User Manual page 48

4. Fb spcx3rum analgzrs with a 50 62 input: Use an external 50 62 to
dc voltages in excess of 25 V and ac power-line voltages in excess of
C A U T I O N
100 Vpeak can permanently damage the analyzer input.
5. Fbr using an edema1 ampli$er (preamp): An external amplifier may be
PEAK 1
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CENTER 57.888
RES BW 38 kHz
75 Q matching pad/de block to compensate for the impedance mismatch
between a 75 fl impedance system and the spectrum analyzer's 50 61 input
impedance. If you use an HP 11981A external pad, the external pad
causes approximately 5.8 dB of amplitude loss. The external pad function
(EXT PAD YES MO ) can be used to compensate for this amplitude loss.
Connect the matching pad to the spectrum analyzer input.
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Press Analyzer Input EXT PAD YES NO to underline YES.
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Press Prev Menu to return to the Setup menu.
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If you are using a spectrum analyzer with 50 fl input impedance but are
not using an external matching pad/de block, the analyzer will compensate
for most of the impedance mismatch, but amplitude measurements can
have up to 3~0.2 dB additional error caused by the uncompensated
mismatch over the frequency range.
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
1993
AT 10 dB
MHz
Figure 2-l. Channel Tuning Menu
Channel Measurements
Making Channel Measurements
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RT
2-5