Keysight NFA Series Noise Figure Analyzers Service Guide 201
RF Section Troubleshooting (N8976B)
RF Section Description
The RF section is comprised of the following major assemblies:
— A9 Input Attenuator A
— A10 Input Attenuator B
— A11 Low Band Switch Assembly
— A12 YTF Preselector
— A13 RF Front End Assembly - shown on the block diagram as A13 and
A13A1, however replacement A13 assemblies include the A13A1.
— A15 Front End Control Assembly
1. RF input frequencies < 3600 MHz
route through the low band path. Refer
to the RF Lowband Path Block Diagram in
for details.
The RF input signal level can be optimized by Input Attenuator A and/or
Input Attenuator B. The low band switch assembly contains a limiter that
offers added protection for the mixer, and routes the input signal to the
low band input of the A13 RF Front End assembly. There are (3) different
signal paths on the input of the RF Front End assembly that the signal can
be routed through depending on installed options and front panel settings.
—
Low Band Preamplifier path, 20 dB nominal gain (Any standard
preamp option)
—
Direct to Mixer #1
The RF input signal is then mixed with the 1st LO from the A20 YTO
assembly to a 1st intermediate frequency of 5122.5 MHz. Since the RF
input signal is <3600 MHz for low band, this RF input signal is upconverted
in Mixer #1 to the 1st IF. This 1st IF signal is then downconverted in Mixer
#2 using the 4800 MHz 2nd LO generated on the A16 Reference assembly
to a 2nd intermediate frequency of 322.5 MHz (5122.5 MHz (1st IF)
−
4800 MHz (2nd LO)). The 2nd IF output is at A13A1J7. This signal path is
used for all frequency range options when the RF input frequencies are
< 3600 MHz. The control voltages and biasing for these assemblies come
from the A15 Front End Control assembly.
Содержание N8973B
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Страница 228: ...228 Keysight NFA Series Noise Figure Analyzers Service Guide RF Section Troubleshooting N8976B Troubleshooting ...
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Страница 350: ...350 Keysight NFA Series Noise Figure Analyzers Service Guide Service and Diagnostics Menus Front Panel Key Test ...
Страница 470: ...470 Keysight NFA Series Noise Figure Analyzers Service Guide Assembly Replacement Procedures Front Frame Assembly ...