Spurs (Including Harmonics) - Agilent Technologies 8711C Service Manual

Re ection tracking is determined from the frequency response of a corrected re ection
measurement. After a one-port re ection calibration has been performed, a re ection
measurement of a male short is made.
If This Test Fails
Directivity is mostly dependent upon:
the quality of adjustment #107
the quality of reference load used in the adjustment
the quality the load used in the test
If directivity fails, repeat adjustment #107 with a known good load (better than 40 dB of return
loss). Source match is mostly dependent upon hardware in the A5 receiver assembly. Any
failures will probably require the replacement of the A5 receiver assembly.
est port match is solely dependent upon the A5 receiver assembly. If either of these two tests
fail, rst inspect the two type-N connectors for damage, especially on 75 units. If the test port
match fails, also suspect the A5 receiver assembly diodes.
It is very unlikely that re ection tracking will fail. However, if re ection tracking does fail,
repeat adjustment #107 with a known good load (better than 40 dB of return loss).

Spurs (including harmonics)

Harmonics and spurs are tested by connecting the analyzer to a spectrum analyzer via a high
quality type-N cable. For 75 analyzers, a minimum loss pad is used to change the impedance
to 50 . he loss through the cable is compensated for automatically. Harmonics are tested at
+7 dBm minus the sum of:
4 dB for the HP 8730A
3 dB for HP 8711C/12C13C/14C Option 1EC (75 )
1 dB for HP 8711C/12C13C/14C Option 1E1 (step attenuator)
2 dB for HP 8711C/12C Option 1DA/1DB (AM delay)
4 dB for HP 8713C/14C Option 1DA/1DB (AM delay)
In-band harmonics are tested at several frequencies. he second harmonic of 700 MHz need
not be tested on an HP 8711C/12C/30A because its upper frequency is 1300 MHz. Out-of-band
harmonics are not tested.
Fractional-N spurs are also tested with this program, as well as some other types of spurs
but generally none of these cause problems. hese type of spurs have typical (characteristic)
speci cations only.
his automated test requires that the spectrum analyzer's and the network/tuner analyzer's
timebases be tied together, so that any known spur will be at the exact frequency expected.
Connect a BNC cable between the spectrum analyzer's EX REF OU to the network/tuner
analyzer's EX REF IN. his saves signi cant time since the program does not have to search
for every signal. he program will rst check that the timebases are connected together
before proceeding. If this test is performed manually, locking the two analyzers together is not
necessary.
If This Test Fails
Note that while many types of spurs are tested, only harmonics are speci ed. If harmonics
should fail, repeat the fractional-N adjustment as well as adjustment #104. he most likely
cause of a failure is the A4 source assembly.
Performance T ests 1-25