INTRODUCTION
The B & K Model 1801 is a high-quality, lightweight,
autoranging counter designed for freguency measurement
in the range from 20 Hz to 40
MHz. A
front panel function
switch selects "1 SEC" preset gate interval or "AUTO"
range. In the AUTO position, the correct gate interval for
maximum resolution without overranging the instrument is
automatically determined and proper frequency unit in
dicators for KHz or MHz turned on. In the "1 SEC"
position, the display will indicate frequency to the closest
Hz even if the leading most significant digit (MSD) is
beyond the display range. The input impedance of 1
megohm is ideal for use with a divide-by- IO probe for
measurements where the source loading is critical.
The display consists of six ?-segment, solid state,
numerical display units and three LED's (light-emitting
diodes) for units and overrange indication.
An internal time base of 10 MHz is generated by a
crystal-controlled oscillator. Provision has been made for
the user to convert the instrument to operate from an
external time base when extreme accuracy is desired.
Consult our Customer Service Department for conversion
instructions.
Rugged, compact design and exceptional accuracy
combine to make this counter a valuable tool for the
scientist, engineer, experimenter, hobbyist, and service
technician. It not only is an excellent instrument for the
laboratory, but also is rugged enough for use in the field.
Low power consumption of under 25 watts facilitates its
use with DC-to-AC power inverter.
SPECIFICATIONS
1. FREQUENCY CHARACTERISTICS
Range
20Hz to 40 MHz (guaranteed); 10
Hz to over 60 MHz ( typical).
Function switch selects kHz or
AUTO display reading
Gate Time, Auto
10 mSEC or 100 mSEC (MHz
reading), or 1 SEC (kHz reading),
chosen automatically
Gate Time, Manual
1 SEC (kHz reading, 1 Hz resolu
tion).
Accuracy
± time base accuracy, ± 1 count.
Resolution
Display
1 Hz
Frequency of input signal with
automatically positioned decimal
point. Units of measurement
(kHz, MHz) displayed in front
panel by illuminated indicator.
2.
INPUT CHARACTERISTICS
4
Impedance
Protection
Connector
Coupling
1 megohm, shunted by 20 pF.
Diode-protected.
BNC (Front Panel)
AC
Sinewave Sensitivity 30 mV rms (guaranteed); 15 mV
rms (typical); 20 Hz to 40 MHz.
Maximum Input
200 V (peak AC+ DC) to 500 Hz;
derate linearly to 100 V (peak AC
+ DC) at 1 kHz.
100 V (peak AC+ DC) 1 kHz to 5
MHz; derate linearly to 50 V
(peak AC + DC) at 40 MHz.
3.
INTERNAL TIME BASE CHARACTERISTICS
(REFERENCED TO 2S
°
C. AFTER 30-MINUTE
WARM-UP)
Type
Frequency
Setability
Line Voltage
Stability
Temperature
Stability
Maximum Aging
Rate
Crystal oscillator
10 MHz
±0.1 PPM (±1 Hz)
Better than ±1 PPM for ±10% line
voltage variation.
Better than ±0.001% (i.e. ±10
PPM)
from 0.50
°
C. ambient.
10 PPM /Year, 1
PPM/
Month.
4. DISPLAY CHARACTERISTICS
Visual Display
6 digits with overflow, kHz and
MHz indicators.
Overflow Indication Flashing light indicates display
range is exceeded.
Display Refresh
Fixed; 200 mSEC plus gate in-
Interval
terval.
S. GENERAL
Power Requirements 105 to 130V, 117V nominal, 60
Hz; 25 watts maximum.
Dimensions
Shipping Weight
Handle
3-5/16" H x 8-11/16" W x 10.l/2"D.
5-1/ 2 lbs.
Combination
"Kick
Stand" and
handle attached to bottom of
unit.
