Instruction Manual

DISPLASY RESOLUTION:
Auto select from 0.001Hz to 1KHz depending
on the frequency.
MAX COUNTER RANGE:
0.1Hz to 50MHZ
MAXIMUM EXTERNAL VOLTAGE
300V dc + ac peak
ACCURACY:
+0.01% + 1 digit or 1/99999 +1 digit
Time Base:
18,432MHz + 10ppm ( 23°C±5°C )
SENSITIVITY:
NOTE:
1. The Counter must be set at ”DC
COUPLING” operation then the input signal
is less than 10Hz.
2. The counter is operated by the “Trigger
Source” CH1, CH2, or EXT.
MODE RANGE SENSITIVITY
2Hz~40MHz ≥1Div
1Hz~45MHz ≥2Div
INT
0.2Hz~50MHz ≥3Div
10Hz~50MHz ≥200mVrms
EXT
1Hz~50MHz ≥400mVrms
2121 Internal Frequency Counter
operating instructions.
The signal from both Oscilloscope channels
(CH1 and CH2.) could be used for frequency
measurements input.
Set VERT and SOURCE switches to selected
channel and synchronize measured signal on
CRT display. Counter will auto sense and
register signal frequency on the counter red
digital display. Flashing red dote in top left
corner of the first digit is Gate indicator. It is
light up every time during frequency counter
is update.
NOTE: If input signal is not synchronized
correctly on CRT display Frequency counter
may have incorrect measurements.
To check power line frequency with the 2121C
set Trigger SOURCE switch to LINE position.
There is no manual synchronization necessary
in this mode, Counter will show Line
frequency automatically.
To activate the dedicated frequency counter
input, separate from Oscilloscope cannels, set
Time /Div switch to any range under red
FREQ.≥100KHz label. Set SOURCE switch
to EXT position. Now 2121C is set to Universal
counter mode. Use the Trigger Level knob to
select correct Counter trigger level. Flashing
red LED on the top left corner of counter
display is indicating the correct trigger level is
set.
NOTE: If trigger level is not set correctly on
and red Led is not ON or flash Frequency
counter may have incorrect measurements.
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