The Fluke Model 1920A Digital Counter is a 5 Hz to 520 MHz
(to 1 GHz or 1.25 GHz, optional) counter de- signe d
primarily for tele communications applications. The unit is
compact and lightweight making it fully portable and
suitable for field use. An optional battery-operated version
of the counter permits use at remote or mobile installations
where AC line power is unavailable.
1-3. The display is nine digits, light-emitting-diode (LED)
type with leading-zero suppression and automatic decimal
point positioning. Display resolution is front-panel
selectable at 1 kHz, 100 Hz, 10 Hz, 1 Hz or 0.1 Hz,
Annunciators are provided to indicate the measurement unit
(i.e. MHz, kHz, or Hz) and also overflow when the capacity
of the display is exceeded. All displayed measurement data
is provided by an optional Data Output Unit (DOU, Option -02).
1-4. Input sensitivity for the 1920A is better than 15 mV
rms and AGC is incorporated to provide stable operation.
Extremely low-level signals which cannot be reliably
measured, fall below the AGC threshold and are ignored by
the counting circuitry. A “burst5’ mode is provided to
permit the measurement of keyed RF signals having a duration
of two milliseconds or greater. The display is automatically
held at zero if the RF burst is of shorter duration than the
selected gate time (resolution).
1-5. The 1920A also incorporates an optional high-
resolution mode (Option- -06) to permit the measurement of
low frequency signals, such as signalling tones, while using
conveniently short gate times, in this mode, input signals
in the range of 10 Hz to 10 kHz are multiplied by a factor
of 1000 allowing the use of shorter gate times for better
1-6. A self-check mode of speration is also provided to
verify proper overall performance of the digital circuitry
and the display of the unit prior to use.
1-7. Several options are available with the Model 1920A.
Each is listed by option number in Table 1-1. Accessories
are listed and described in Table 2-1. Desired options must
be specified at time of purchase. A detailed description of
each option is included in Section 6, Options and Accessories.