Keysight N9912A Service Manual page 48

Theory of Operation
Measurement Group
CAT/NA RF Section
In this section, the 30 MHz time base from the A5 system board is used to
generate a source signal in the source synthesizer that covers the frequency
range of 100 kHz to 6.2 GHz.
The source signal is generally rich in harmonic content. This is acceptable
because the signal is used with tuned receivers.
The source frequency bands are listed below:
1
2
3
4
5
6
7
The RF Out attenuator between the source and the reflectometer has two
settings: nominal values of 0 dB and 30 dB. The setting is determined by the
Hi/Lo power setting on the user interface.
The reflectometer performs three functions:
— It passes the source output signal to the RF OUT port.
— It samples the source output to the RF OUT port.
— It samples the incoming signal at the RF OUT port.
The sampled signals are mixed with the LO signal to produce two 290 kHz IF
signals, NA-A and NA-R.
The reflectometer dissipates up to 1.5 watts when active.
The RF OUT port has a DC isolation capacitor (0.056uF).
SA RF Section
In this section, the signal at the RF IN port is first routed through a DC isolation
capacitor (0.056 uF) then through the RF In attenuator.
RF In Attenuator
The RF In attenuator covers the range of 0 dB to 31 dB in one dB steps. An
adjustment determines compensation for each of the 32 steps over 11
frequency bands (see
provides nominal 1.0 dB steps.
5-8
100 kHz to 1.6 MHz
1.6 MHz to 25 MHz
25 MHz to 0.2 GHz
0.2 GHz to 0.8 GHz
0.8 GHz to 1.6 GHz
1.6 GHz to 3.2 GHz
3.2 GHz to 6.2 GHz
"SA Frequency Bands" on page 5-9).This compensation
Keysight N9912A Service Guide