224 Keysight N9038A MXE Service Guide
RF Downconverter Section
RF Downconverter Section Description
In this case the input signal is mixed with 4 times the output frequency of the
A14 LO Synthesizer assembly to generate the 322.5 MHz 1st IF.
The 322.5 MHz 1st IF output exits the A13 RF Front End assembly at J7.
Band 6 Signal Path - Input Frequencies from 34.4 to 44.0 GHz
(Option 544)
RF input frequencies from 34.4 to 44.0 GHz go through the band 6 path. Refer
to Chapter 15, “Block Diagrams.” for details.
The RF input signal entering the instrument through the RF Input connector is
routed through both of the instrument's input attenuators (A9 & A10). The
signal is then routed through the SW2 Transfer switch, where it could either be
directed through the RF Preselector section of the instrument or bypass it.
However, Since the RF Preselector only operates up to 3.6 GHz, frequencies in
this range will always be bypassed. The output of the transfer switch is then
routed to the A11 RF Switch / High Band Preamp assembly.
There are two different signal paths in the A11 RF Switch / High Band Preamp
that the signal can be routed through, either through the high band preamp or
around it. The high band preamp has a gain of approximately +30 dB. The
signal is then routed to the A12 YTF Preselector.
After passing through the A12 YTF Preselector the signal is then routed to the
A13 RF Front End assembly. The input switch in the A13 RF Front End
assembly routes the RF input signal to the correct 1st mixer for the current
tuned frequency.
The RF input signal is then mixed with the fourth harmonic of the 1st LO from
the A14 LO Synthesizer assembly after it has been doubled in frequency on the
A13 RF Front End assembly to generate a 1st IF of 322.5 MHz.
1st IF = (1st LO x 4) - RF = 322.5 MHz
In this case the input signal is mixed with 8 times the output frequency of the
A14 LO Synthesizer assembly to generate the 322.5 MHz 1st IF.
The 322.5 MHz 1st IF output exits the A13 RF Front End assembly at J7.
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