441A152 PEAK METER 3
Manual 23528 Rev. A
ECN 50523
When the unit is powered up, it automatically returns to the
state it was in when last powered down.
A more detailed discussion of the individual components
follows.
Input
The input signal is fed to the peak meter via the input BNC
connector on the front panel or via the back plane within the
chassis when used in conjunction with PCB Model 443 series
dual mode amplifier.
Note: Back plane option is not available while in ICP®mode.
Coupling (Hi Pass Filter)
AC or DC coupling option is provided. When the unit is in AC
coupled mode, the low frequency cutoff is approximately
0.05Hz. This translates into a Discharge Time Constant (OTC)
of approximately 10 seconds. AC coupling should be selected
if it is desired to block DC voltages, or those voltages that fall
below the 0.05Hz cutoff frequency. AC coupling may also
reduce the effects of temperature-induced signals.
Note: DC coupling is not available while in ICP® mode.
Gain
The circuitry associated with gain selection only affects the
PEAK and the DVM readings. While the unit is measuring BIAS
or TRUE OUTPUT, the gain is always 1.
Alarms
The alarms can be configured to trip the relays if the input
voltage is above or below a preset voltage. If the unit is
operating in TRUE OUTPUT mode, the alarm thresholds may
also be a negative number.
Note: The alarm function is deactivated if in BIAS mode.
Overload Detector
The overload detector monitors the input, the output of the
gain stage, and the input of the peak detector, so overload in
various parts of the circuitry are not masked by coupling. The
overload indicator is located on the front panel.
Peak/DVM Output
The Peak/DVM output is a DC voltage equivalent to the Peak,
DVM, or TRUE OUTPUT voltage that is displayed on the LCD.
This voltage is available via a BNC on the front panel.
Note: The Peak/DVM output is deactivated if in BIAS mode.
Analog Output
The analog output BNC on the front panel allows the user to
observe the input signal with a storage oscilloscope or other
recording device. This voltage is inherently AC coupled with
the cut-off frequency approximately 0.05Hz.
PEAK HOLD Operation
In its simplest form, the Model 444A151 Peak Meter displays
a peak reading, and keeps that reading until a higher peak
comes along or the reset is activated.
Connect the output of the signal source to the input BNC (or
back plane as discussed in section 3.1). It is recommended to
activate the reset before the first measurement is performed.
It is further recommended to allow sufficient warm up time
after powering up the unit.
The meter is now ready to accept, hold, and display the peak
value. After the initial pulse or peak has occurred and before
the meter has released the reading (reset), should another
smaller pulse be applied to the input, nothing will happen.
However, during this interval, should a higher pulse or peak
be applied, the meter will update to this higher peak and hold
the new value.
Manual RESET
The RESET function zeroes out the current peak voltage, as
well as zero out the PEAK/DVM BNC voltage. The Manual
RESET can be achieved by pressing the front panel button or
by activating the remote reset. The reset function may be
performed from a remote location if desired. Connect a co-
axial cable to the "REMOTE RESET" BNC jack and connect the
other end of the cable to a normally open switch contact.
Momentarily closing the switch will activate the reset.
Automatic (Timed) RESET
The Automatic RESET is performed by a 'countdown' timer,
which is displayed on the LCD. This option can only be
selected if the peak meter is set to PEAK HOLD mode. If this
option is selected, the user is prompted to input the time in
seconds (range is from 01 seconds to 99 seconds). The reset
is activated once the 'countdown' reaches "00". If the front
panel reset or remote reset is activated while in Automatic
RESET mode, the countdown timer is reloaded.
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