ORTEC 420 - Input and Output Connectors

4-2
DIFF./INT. Switch (32)
Switch 52 determines whether the unit shall be on integral timing discriminator or
o timing single channel analyzer. When this switch is in the DIFF. position all
signals which trigger the AE discriminator will prevent the logic signal created by
the timing discriminator from reaching the output, and therefore there will be no
output from the unit. When the switch is in the INT. position, the AE discriminator
is disabled, and all signals which exceed the lower level threshold will create an
output signal.
WALK Adj.
Due to minor circuit differences, various amplifiers will have a true crossover at
different values of voltage, but very near zero. For this reason, a WALK adjust
ment is provided on the front panel. This is a screwdriver adjustment and is
adjusted to an optimum value with a Model 410 Amplifier before the unit leaves
the factory. For information concerning the method of adjustment, refer to "Cali
bration Adjustment," Section 6.1 of this manual.
4.2 Initial Testing and Observation of Waveforms
Refer to Section 6.1 for information on testing performance and observing wave
forms.
4.3 Connector Data
CN1 — INPUT (BNC) Connector
CN1 has input impedance of 2000 ohms, oc-coupled, and a maximum input of
10 volts. To minimize reflections when driving into CNl from a low impedance
voltage source such as the output of the Model 410, etc., CNl should be extern
ally terminated in the characteristic impedance of the connecting coaxial cable.
CN2—OUTPUT NEG. (BNC) Connector
Output driving source impedance is less than 10 ohms. The signal is dc coupled
starting from zero volts; it is the standard ORTEC Fast Negative logic signal and
is used for optimum timing resolution.
CN3 —OUTPUT POS. (BNC) Connector
Output driving impedance is less than 10 ohms. The signal is dc coupled starting
from zero volts; it is the standard ORTEC positive logic pulse whose application
is normally coincidence timing and analyzer gating.
OUTPUT Test Points
Oscilloscope test points for monitoring output signals are available at each
OUTPUT BNC. Each test point has a 470-ohm series resistor connecting it to the
respective OUTPUT BNC connector.