EG&G ORTEC 474 Operating And Service Manual - Page 6

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ORTEC 474 TIMING FILTER AMPLIFIER
1.
DESCRIPTION
The ORTEC 474 Timing Filter Amplifier is a NIM-standard
module for use where a wide-band fast, variable RC filter
amplifier with high drive and variable gain is needed. Fea
tures of the 474 include a wide gain-control range, sepa
rately selectable RC integrate and differentiate time
constants in the nanosecond region, pole-zero com
pensation, and drive capability sufficient for use with
son or icon systems.
The input signals are dc coupled into an impedance of
about icon. The acceptable amplitude range for the
linear input, to retain its linearity, is Oto ±1 V. The 474can
operate with an input dc offset where the maximum total
input signal range, including the offset, does not exceed
the limits of ±5 V. Input signals may be either positive or
negative unipolar, or they can be bipolar with either a
positive or negative lobe leading. The output polarity can
be switch-selected to either duplicate or invert the input
polarity. Protection is provided for input voltages of up to
±100 V at a 10% duty cycle integrated over 1 second.
The gain for midband frequencies can be set at any value
from X2 through X250, using six coarse gain settings and
a fine gain control, which is a single-turn potentiometer.
The gain factors are selected to provide range overlap and
to assure continuously adjustable gain control through
out the full range.
Two 6-posltlon switches permit the separate selection
of RC-integrate and RC-dlfferentlate time constants. The
integrate time constant can deselected from 10 ns (switch
set at Out) through 500 ns. The differentiate time constant
can be selected from 20 ns through 500 ns or, when set at
Out, at 150 MS. Thus the input pulses can be reshaped to
provide a consistent risetlme and decay time for compati
bility with the application requirements.
The linear output pulses can be either unlpolaror bipolar,
depending on the type of Input pulses that are furnished
to the 474. When the front panel toggle switch selects
Invert, the output Is the opposite polarity to the input or,
when the toggle switch selects Noninvert, the polarities
are the same. The 474 is capable of driving a 500 load up
to ±5 V with no degradation of the performance specifi
cations.
The ORTEC 474 Timing Filter Amplifier Is a NIM-standard
single-width module; the front panel measures 1.35 by
8.714 In., which is in accordance with TID-20893 (Rev). It
is intended for installation and operation in a standard
enclosure, suoh as the ORTEC 401/402 Series of Bins and
Power Supplies. The module accepts all of its required
operating power from the power supply that Is attached to
the bin.
2.
SPECIFICATIONS
2.1.
PERFORMANCE
INPUT AMPLITUDE RANGE 0 to ±1 V linear signal, 0 to
±5 V offset, maximum input ±5 V total.
OUTPUT AMPLITUDE RANGE 0 to ±5 V linear onto a
50n cable and load.
RISETIME <10 ns with filter Out, or -2.2 r, for other
Integrate settings.
NOISE
For maximum gain, rms noise referred to the
input is ^10 mV with n = rd = 200 ns, or<50 mV with filter
Out; measurements made with an HP 3400A true rms
meter.
NONLINEARITY <±0.05% at midband frequency over
±5 V range.
TEMPERATURE INSTABILITY
DC Level <±25 mV/°0 referred to the output.
Gain
<0.06%/° 0.
OPERATING TEMPERATURE RANGE 0 to 50° C (273
to 323 K).
2.2.
CONTROLS
COARSE GAIN
Front panel 6-posltion switch to select
XI, X2, X4, X6, XI0, or X20 gain factor.
FINE GAIN
Front panel single-turn potentiometer, con
tinuously adjustable from X2 to XI 2.5.
POLE ZERO ADJUST Front panel screwdriver adjust
ment to cancel the pole associated with the input signal
such as that derived from the preamplifier clipping net
work.
DIFFERENTIATE
Front panel 6-posltlon switch selects
a differentiation time constant to control the decay time
of the pulse; settings select Out (equivalent to 150 ms), 20,
50, 100, 200, or 500 ns.
INTEGRATE
Front panel 6-posltlon switch selects an
integration time constant to control the risetlme of the
pulse; settings select 20, 50, 100, 200, or 500 ns or Out
(equivalent to 10 ns).
Note; With DIff and Int switches both at Out, passband is
typically 1 kHz to 35 MHz.