HP 8901B

Operation Model 8901B
COMMENTS
Input/Output Status
When the instrument is measuring IF frequency, the signal at MODULATION OUTPUT/AUDIO
INPUT remains unchanged.
Relative Measurements
If IF frequency is to be displayed relative to a reference, enter the ratio reference using the RATIO key.
(Refer to
Ratio on page 3-215.)
Frequency Resolution
Normally, the counter updates the display five times each second. For selection of other resolutions,
use Special bction
7. (Refer to RF Bequency Resolution on page 3-131.) Counter accuracy is the
reference accuracy
f3 counts.
IF Filter Selection
IF filter selection is dependent on the selected IF Frequency. (Refer to Filters, RF and IFon page 3-229.)
When using the 455 kHz IF on input signals with frequencies greater than 300 MHz, incidental AM
(that is, AM due to FM) increases substantially.
RF Input Frequency Calculation
The Modulation Analyzer determines the frequency of the RF input signal by counting the frequencies
of both the
IF and LO and calculating their difference.
IF Frequency Accuracy
The IF frequency need not be exactly its nominal value in order to guarantee accurate modulation
measurements. Unless specifically overridden by Special Function
8 or DISABLE ERROR (Blue
Key,
RANGE HOLD), Error Messages safeguard the measurements. (Refer to Error Message Disable
Control
on page 3-233 and RF Bequency Thing on page 3-115.)
3-126 IF Frequency