Chapter 4 99
Troubleshooting the RF Section (E4446A, E4447A, E4448A)
RF Section Description (E4446A, E4447A, E4448A)
Verifying the A21 FELOMA Assembly
First check that the YTO signal is present at the LO IN connector by
measuring the power at the cable from the YTO. The signal should be
3-7 GHZ at +12 to +17 dBm.
Next verify the signals at the LO outputs. The Lowband, RYTHM, LO
Out and Sampler outputs all range from 3 GHz to 7 GHz. The SBTX
output is doubled, and will range from 6 to 14 GHz.
Table 4-3 lists the LO power at the different FELOMA output ports.
To verify the SBTX output at J2, set the PSA to a center frequency
above 26.8 GHz and set the span to zero Hz.
Verify the RYTHM output at J3 by setting the center frequency of the
PSA from 3 GHz to 26.5 GHz while in zero span. Notice the table
includes some approximate out of band measurements, shown in italics,
that can be useful if you suspect a port-to-port isolation problem.
Verify the Lowband output at J4 by setting the center frequency of the
PSA from 3 Hz to 2.85 GHz while in zero span. Again, additional out of
band values are given for isolation purposes.
Verify the Sampler output and the 1ST LO outputs while in zero span.
Currently the J6 LO Output is not leveled.
Table 4-3 Example measurements for FELOMA outputs
PSA
Center
Frequency
J2
SBTX
Power/Fre
q
J3
RYTHM
Power/Freq
J4
Lowband
Power/Freq
J5
Sampler
Power/Freq
J6
1
st
LO Out
Power/Freq
50 MHz NA −21 dBm
3.971 GHz
(typical)
+14 dBm
3.9714 GHz
−14 dBm
3.971 GHz
+14 dBm
3.971 GHz
10 GHz NA +13 dBm
5.161 GHz
−25 dBm
5.161 GHz
(typical)
−9 dBm
5.161 GHz
+13 dBm
5.161 GHz
30 GHz +13 dBm
13.040 GHz
−14 dBm
6.519 GHz
(typical)
−17 dBm
6.519 GHz
(typical)
−11 dBm
6.519 GHz
+15.95 dBm
6.519 GHz
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