BANDP
ASS CAVITY
TUNING
Use this procedure to peak-tune bandpass cavities, duplexers, crystal filters and other bandpass devices. Tune the band-
pass to center frequency. After tuning, use normal gain or loss measuring techniques to measure insertion loss.
1.
Connect
the
Analyzer
to
the
device
under
test,
as
shown in figure 4-20. When tuning a single cavity, connect the RF
In/Out
to the cavity's output connector. When tuning a bandpass duplexer, connect the RF
In/Out
to the duplexer's
antenna port.
2.
Set DISPLAY to Duplex Gen, FUNCTION switch to Generate, and attenuator to -lOdb.
3. Change the FUNCTION switch to Monitor. Enter pass frequency on the display. Set the offset to 0 MHz.
4. Change DISPLAY to Spectrum Analyzer. Set Dispr/Sweep control fully clockwise to
10
MHz. Turn the Duplex
Generator
on.
5. Tune the cavity, or both cavities in the duplexer leg, to a peak indication on the display's center graticule. The single
cavity
is
ready for service.
6.
For duplexer tuning, move the output cable from the Duplex Oen Output connector to the duplexer's other end.
Repeat steps 2 through 4.
Put
the duplexer into service. Check the duplexer for insertion loss according to its
specifications.
4-36
"----"
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