HP E42 manual Model 5328A Operation Channel C Input, Channel Overload lndicator

Model 5328A

Operation

3-49.Channel C Input

3-50. The CHANNEL C 500 MHz 500 input is useful for higher frequency signals out of the A and B input channel range (0 to 100 MHz).

CAUTION

The “C” channel input signal should be limited to 5 volts maximum.

If this limit is exceeded the inline fuse may open (blow).

3-51.“C” Channel Overload lndicator

3-52. The OVERLOAD (CHANNEL C) indicator will flash on and off if the voltage maximum is exceeded at the “C” channel input.

3-53.Hysteresis Band of Trigger Levels

3-54. The width of the trigger level hysteresis band, shown in Figure 3-77is determined by the sensitivity of the counter. For frequencies below 40 MHz, it is typically less than 25 mV peak-to- peak. At frequencies from 40 MHz to 100 MHz, it is typically less than 70 MHz peak-to-peak. The signal must pass through the entire hysteresis band before a trigger pulse is generated. If the SLOPE switch is set to “+”, the trigger pulse occurs at the top of the hysteresis band. If the SLOPE switch is set to “-”,the trigger pulse “occurs at the bottom” of the hysteresis band.

Figure 3–11Hysteresis Band

3-55. Since trigger level measurements indicate the center of the hysteresis band, a better value for the actual trigger level may be obtained by subtracting one-half the hysteresis band (“-” slope) or adding one-half the hysteresis band (“+” slope). A typical value for the width of the hysteresis band is 30 mv peak-to-peak.

3-56 The value to use for the hysteresis band depends on the frequency; or, for pulses, it de- pends on the rise time.

3-57.External Frequency Standard Input

3-58. The rear panel external frequency standard (EXT OSC IN) input is useful for locking the counter to a high stability external frequency standard. This external standard must be 1, 2.5,5, or 10 MHz, with an amplitude of >1V rms into 1 kfl (maximum input of 5 volts peak-to-peak).

3-12