HP 8901B Operation And Calibration Manual page 70

1-6 Frequency Counter
Choosing a
Tuning Mode
Proper tuning is the key to making successful RF Frequency as well as other
tuned measurements with the HP 8901B. The optimum tuning mode for
your measurement will depend on the characteristics of the input signal.
automatically tune to the new input signal. (Note that four dashes are
placed in the display while the HP 8901B is tuning to the input signal.)
3.
Adjust your signal generator to
110
MHz. The HP 8901B should
Manual Tuning Mode
4.
5.
Auto Tuning Mode
6.
Track Mode
7.
8.
Key
110
MHz into the HP 8901B by pressing the digit keys 1 1 0 and
the
MHz
key. Note that AUTO TUNING (the green LED) is now off. By
keying in an RF frequency and pressing the
MHz
key, you have selected
the instrument's Manual Tuning mode. The HP 8901B's tuning is now set
at 110 MHz.
The Manual Tuning mode can also be selected by pressing the
MHz
key by
itself. When you press the
MHz
key without keying in a frequency value,
the HP 8901B's tuning is set at the frequency currently being displayed.
Adjust your signal generator to
112
MHz. The HP 8901B
will
display
an Error 01 to let you know that the input signal is no longer within the
tuning range of the frequency
(1
10 MHz) that the instrument was manually
set to.
Press the Blue
Shift
key and the
AUTO TUNING (TRACK MODE)
key. You have placed the instrument back in its Auto Tuning mode.
(Notice that the AUTO TUNING, green LED is on again.) The HP 89018
is now tuned to the frequency of the input signal. (The Auto Tuning
mode is the right choice when measuring a single, stable input signal.)
Press the
TRACK MODE
key. In Track Mode, the HP 8901B is locked to the
input signal.
Increment your signal generator from
112
M H z to 100 M H z in
1
MHz
steps. The HP 8901B is now able to track the input signal as it changes
frequency. (Track Mode is the right choice when you are measuring a drifting
or noisy signal.)
Tuning Mode
to
Select
Input Condition
Measurement
Selected
Single, stable signal
MultiDle. stable sianals
I
Manual Tunina
I
Auto Tuning
RF
Freauencv.
I .
. ,
-
-
Modulation or Single, drifty or noisy
Auto Tuning
Audio sianal
>
10
MHz Track Mode
Multiple, drifty or noisy Manual Tuning
I
sianals
>
10
MHz
I
Track Mode
Frequency Error All Cases Manual Tuning
or RF Power
HP 8901B Operation
Tuning set at manually tuned frequency
Tuning locked to input signal