Service manual

4
2. SPECIFICATIONS
2.1. PERFORMANCE
GAIN RANGE Continuously adjustable from 5 to
1250.
PULSE SHAPE Semi-Gaussian on all ranges with
peaking time equal to 2.2
, 50% pulse width equal
to 3.3
, and pulse width at 0.1% level equal to 4.0
times the peaking time. Bipolar crossover = 1.5
.
INTEGRAL NONLINEARITY <±0.05% for 1.5-
s
shaping time.
NOISE <5
V rms referred to the input using 3 s
unipolar shaping; <7
V using 1.5 s shaping; both
for a gain
100.
TEMPERATURE INSTABILITY
Gain
±0.0075%/°C, 0 to 50°C.
Dc Level
±30 V/°C, 0 to 50°C.
WALK
±5 ns at 0.5 s shaping for 50:1 dynamic
range, including contribution of an ORTEC 551 or
552 Constant-Fraction Timing Single-Channel
Analyzer.
OVERLOAD RECOVERY Recovers to within 2%
of rated output from ×300 overload in 2.5
nonoverload pulse widths using maximum gain for
unipolar output. Same recovery from ×500 overload
for bipolar.
RESTORER Gated active baseline stabilizer with
automatic threshold circuit to provide the threshold
level as a function of signal noise to the baseline
restorer discriminator.
SPECTRUM BROADENING* Typically <10%
FWHM for a
60
Co 1.33-MeV gamma line at 85% of
full scale for an incoming count rate of 1 to 50k cps.
Unipolar output, 1.5
s shaping.
SPECTRUM SHIFT* Peak position shifts typically
<0.02% for a
60
Co 1.33-MeV gamma line at 85% of
full scale (measured at the unipolar output, 1.5
s
shaping, 1 to 50k cps).
*These count rate specifications were measured with a 10% HPGe detector.
Detectors with a large number of slow, rise-time signals will most likely give poorer
results.
2.2. CONTROLS
FINE GAIN Ten-turn precision potentiometer with
graduated dial for continuously variable direct-
reading gain factor of ×2.5 to ×12.5.
COARSE GAIN Six-position switch selects
feedback resistors for gain factors of 2, 4, 10, 20,
40, and 100.
SHAPING TIME Three-position printed wiring
board (PWB) jumpers, easily accessible through
side panel, select time constants for active pulse-
shaping filter network of 0.5, 1.5, or 3
s.
POS/NEG Toggle switch selects either Pos or Neg
input pulse polarity.
PZ ADJ Screwdriver adjustable potentiometer to
set the pole-zero cancellation to compensate input
decay times from 30
s to .
2.3. INPUT
INPUT BNC (UG-1094A/U) front and rear panel
connectors accept either positive or negative pulses
with rise times of 10 to 650 ns and decay times of
30
s to ; Z
in
= 1000 dc-coupled; linear
maximum 2 V; absolute maximum 20 V.
2.4. OUTPUTS
UNI Front panel BNC connector with Z
o
<1 and
rear panel connector with Z
o
= 93 . Short-circuit
proof; full-scale linear range of 0 to +10 V; active
filter shaped; dc-restored with dc level adjustable to
±25mV.
BI Front panel BNC connector with Z
o
< 1 and
rear panel connector with Z
o
= 93 . Short-circuit
proof; positive lobe leading and full-scale linear
range of 0 to +10 V; active filter shaped.
PREAMP POWER Rear panel standard ORTEC
power connector (Amphenol 17-10090) mates with
captive and noncaptive power cords on all ORTEC
preamplifiers.
2.5. RELATED EQUIPMENT
The ORTEC 575A Amplifier accepts linear pulses
from, and furnishes power to, any standard ORTEC
preamplifier or equivalent. Its output pulses may be
used for linear signal analysis, using any of the