RF
Frequency and Frequency
Error
5-3
Mu/fi-channe/
Testing
Use the HP
8901B
to quickly measure an evenly spaced multi-channel
transmitter (such as a
CB
radio).
1.
Adjust the transmitter to
its
first (lowest) channel and connect its output
to the
HP
8901B.
2.
Select the desired measurement on the
HP
8901B and manually
tune it to the frequency
of
the transmitter's first channel. If the
HP
8901B
displays Error
01
(IF
Frequency not centered), key in
8.1
SPCL
to disable the error
so
you can read the measurement.
3.
Key an increment value into the
HP
8901B equal to the channel spacing
of
the transmitter and then press
fi
kHz
key. (For example, press the digit
keys
25
and then the
fi
kHz
key to increment in
25
kHz
steps.) From now
on
just
press the
fi
kHz
key each time
you
want
to
increment up by
25
kHz.
4.
Adjust the transmitter to its next channel. The HP
8901B
will
display
the measured value for the next channel. (Press the
Blue
Shift
key and the
DISPLAY
FREQ
key if
you
wish
to
check the HP
8901Bs
tune setting.)
5.
Continue to adjust the transmitter and then increment the
HP
8901B to
check each
of
the remaining channels.
Frequency
Error
(ppM)
The HP
8901B's
Ratio Mode allows you to verify frequency accuracy
specifications given in parts-per-million.
1.
Connect the
HP
8901B to the output
of
your signal source, and manually
tune the
HP
8901B to the expected output frequency
of
the source.
2.
Select Frequency Error on the
HP
8901B. To increase display resolution to
10
Hz, key in
7.1
SPCL.
3.
Key one-tenth the manually tuned input frequency value (from step
1)
into the
HP
8901B and then press the
RATIO
key. (For example,
if
the
manually tuned frequency was
179.0
MHz, you would key in
17.9
and then
press the
RATIO
key.)
4.
The
HP
8901B
is
now displaying frequency error in parts-per-million.
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