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Model 5328A
Operation
3-70.
The A and B input amplifiers have independent LEVEL, SLOPE, and ATTEN controls
regardless of the mode of operation (SEP or COM A).
3-71.
Signal Conditioning (Standard and Option 040)
3-72.
AC-DC SWITCH.
The AC-DC switch controls the coupling of the external signal to the
attenuator-amplifier by switching a capacitor in series in the AC position or by direct coupling in
the DC position.
The obvious advantage of AC coupling is to provide a DC block for signals
containing
a DC component.
AC has the disadvantage of being unable to pass low frequency
signals (below 20 Hz for the 5328A). A distinct advantage of having DC coupling cover the full
bandwidth (DC-100 MHz) is that extremely accurate time interval or pulse measurements can be
achieved even though pulse widths or repetition rates vary since the trigger point is independent
of the duty cycle of the input signal.
3-73.
ATTENUATOR.
The attenuator (ATTEN) connects the input signal directly to the amplifier
(in X1) or through a 10:1 attenuator (X10) or a 100:1 attenuator (X100) to increase the voltage range
by 10 or 100 times to allow measurement of high level signals that would otherwise be impossible
without external attenuation.
The Option 040 ATTEN
is X1, X2, or X20.
3-74.
SLOPESWITCH.
The +SLOPE switch (provided for each channel) determines which slope
of the input signal will trigger the counter. As
asimple example, (Figure 3-16) if the pulse width of
a positive pulse is to be measured, the A channel slope switch would be set to "+" and the B
channel would be set to "~' (for time interval measurements the A channel always begins the
measurement and the B channel ends the measurement).
POSITIVE
SLOPE
A
' NEGATIVE
SLOPE
PULSE WIDTH
INTERVAL
MEASURED
Figure 3-16.
Slope Switch Settings
NOTE
A simple pulse width measurement is achieved with the
use of the +SLOPE setting for channel A and the ~SLOPE
setting for channel B.
3-75.
The LEVEL control for each channel is adjustable over the range of +2.5V dc with the
attenuator for that channel in the X1 position.
A typical use of the LEVEL controls is shown in
Figure 3-17. The trigger level may be read by the Option 020 or 021 digital voltmeter. Trigger level
measurements are discussed under DVM measurements in Paragraph 4-24.
3-23
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