-2. The John
Fluke Model
7220A is a nine-digit portable,
bench-type
Counter that provides wide-range frequency
measurement capability up to 1300 MHz. There are two input
channels. The ac-coupled Channel A input allows frequency
measurements from 10 Hz to 125 MHz with I Megohm input
impedance. The Channel B input allows prescaled frequency
measurements of continuous wave or burst signals from I00
MHz to 1300 MHz with 50 ohm input impedance. Channel A
signal conditioning includes a X 10 fixed attenuator and a
X10 variable attenuator. For low frequency measurements, a
100 kHz low-pass
Filter may be selected. Four standard
resolution .settings and gate times may be selected that
allow resolution in decade steps from 100 Hz to 0.1 Hz. Four
additional resolution settings (up to .0001 Hz) are
available when the Resolution Multiplier Option-351 is
installed.
1-3. Measurements are displayed on a nine-digit LED display.
Three LED annunciators indicate gate time, measurement
overflow, and if optional oven time base is receiving power.
The
7220A may be operated with the standard 10 MHz timebase,
an optional TCXO (Temperature Compensated Crystal
Oscillator) time base, or either of two optional low power
oven time bases. A self check mode applies the time base
signal to the internal counters, thus providing a check for
most of the
7220A internal circuitry.
1-4. The
7220A is enclosed in a PTI (Portable Test
Instrument) case which includes an inner metal lining for
RF1 shielding. The
Counter may be operated at switch
selectable line voltages of 100V, 120V, 220V or 240V at
47-63 Hz, or with an optional battery pack.
1-5. OPTIONS AND
Accessories
l-6. When the Battery Pack Option -0I0 is installed along
with one of the optional oven time bases, high
measurement accuracy is provided with portable convenience.
When the Digital
Interface Option -521 is installed in the
7220A, serial BCD data is available at a rear panel output.
Option -521 also allows the
Counter to operate directly into
a
Fluke 2020A, 2021 A, or 2030A Printer (with Option -004
installed in the Printer). When Option »521 is installed in
the
7220A
and it is used with a
Fluke I120A Translator with
Option -522 installed (in the 1120A), the
7220A is
compatible with the IEEE-488 Bus. All of the options are
described in detail in Section 6. Tables 1-1 and 1-2 list
the available options and
Accessories for the
7220A,
Comments