Reference
CMC251 User Manual
15
CAUTION.
To avoid damage to the CMC251 Frequency Counter,
ensure that the maximum voltage into the rear panel external input is
no more than +5 V (TTL logic level).
2. Connect a TTL logic low level (0 volts) to the external input
connector.
NOTE
. Shorting the external input connector to ground accomplishes
the same task as applying a TTL logic low.
3. The display reading indicates the negative pulse width. Changing
the TTL logic level to high (+5 V) enables the frequency counter
to measure the positive pulse width.
Counting Events
The CMC251 Frequency Counter can be used to count signal events.
This feature can be controlled remotely with the use of TTL logic
levels applied to the external input connector located on the rear
panel. Refer to Remote Control of TOTAL Mode on page 16 for a
description of its use.
1. Determine the signal voltage level. A good practice is to display
the signal on an oscilloscope and obtain the peak voltage level.
2. Set the Channel A INPUT VOLTAGE switch as necessary,
determined by the voltage reading obtained in Step 1.
3. Press the FUNC button until TOTAL is indicated by a lighted
LED.
4. Connect the signal to the CHANNEL A INPUT connector.
The frequency counter will start counting events immediately and
continue until the signal is disconnected.
Pressing the HOLD button freezes the display, but the count
continues internally. The display will update when the HOLD button
is toggled out and the count resumes.
Summary of Contents for CMC251
Page 1: ...User Manual CMC251 1 3 GHz Frequency Counter 070 8527 03...
Page 4: ......
Page 10: ...General Safety Summary vi CMC251 User Manual...
Page 18: ...Getting Started 8 CMC251 User Manual...
Page 28: ...Reference 18 CMC251 User Manual...
Page 34: ...Appendix A Specifications 24 CMC251 User Manual...