150 N9030B PXA Signal Analyzer Service Guide
RF Section Troubleshooting (RF/Microwave Analyzers)
RF Section Description
2. RF input frequencies from 3.6 GHz to 13.6 GHz go through the high band
path. Refer to the RF Highband Path #1 Block Diagram in Chapter 13for
details.
The input signal level can be optimized by Input Attenuator A and/or Input
Attenuator B. The Low Band Switch assembly routes the signal through
the A12 YTF Preselector. If one of the optional high band preamps is
licensed, the signal can be routed through the preamp. The A15 Front End
Controller provides switching signals.
The Low Band Switch assembly performs the following tasks:
— Provides a limiter that offers added protection for the mixer and
optional preamp.
— Contains the high band preamp.
— Routes the input signal to the A12 YTF Preselector. If Options LNP or
MPB are installed, the signal is routed through switches.
The high band input switch in the Front End Assembly routes the RF input
signal to Mixer #2, where it mixes with the LO and provides a 1st
intermediate frequency of 322.5 MHz. The 322.5 MHz IF output is at
A13A1J7. This is the signal path for Option 508, 8.4 GHz Frequency Range,
Option 513, 13.6 GHz Frequency Range, and Option 526, 26.5 GHz
Frequency Range (up to 13.6 GHz). The control voltages and biasing are
provided by the A15 Front End Control Assembly.
3. RF input frequencies from 13.6 GHz to 26.5 GHz go through the high band
path. Refer to the RF Highband Path #2 Block Diagram in Chapter 13for
details.
The signal path for 13.6 GHz to 26.5 Ghz operation is almost the same as
the 3.6 GHz to 13.6 GHz path. The only difference is that Mixer #3 is used
in this path. The LO is doubled at tuned frequencies above 17 GHz.
A9 Input Attenuator A
This assembly has two 2 dB attenuator sections, a DC block and a cal signal
input port. With the DC block switched in (AC coupled mode), the low end
minimum frequency range increases from 3 Hz to 10 MHz due to capacitive
effects.
A10 Input Attenuator B
This assembly has a total of 66 dB of attenuation to control the signal level into
the Low Band Switch assembly. There is a 6 dB, 10 dB, 20 dB, and 30 dB
section in the A10 assembly. Total input attenuation with the A9 and the A10
combined is 70 dB in 2 dB steps.
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