EG&G ORTEC 414A Bedienings- en onderhoudshandleiding - Pagina 7
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Pagina afdrukken2.3. INPUTS
Coinc Front panel BNC connectors provide 3 ac-coupled
coincidence inputs (A,B,C) of positive polarity; 2-V
threshold, 20-nsec
minimum
width
required; absolute
maximum input 50 V; impedance >300Qfi.
Anticoinc Front panel
BNC connector provides one
dc-coupled
anticoincidence
input (D) for
inhibiting
coincidence output; +2-V threshold, 20-nsec minimum
width required; absolute max input 50 V; impedance
>3000n.
2.4. OUTPUTS
Outputs Two seperate buffered coincidence output signals
through BNC connectors on front panel provide positive
pulses 500 nsec wide with 5-V minimum amplitude;
ac-coupled with <10^2 impedance; monitored through
oscilloscope test points on front panel.
2.5. ELECTRICAL AND MECHANICAL
Power Required
+24 V, 30 mA; -24 V, 30 mA;
+ 12 V, 120 mA;-12 V, 85 mA.
Weight (Shipping) 4.4 lb (2.0 kg).
Weight (Net) 2.4 lb (1.09 kg).
Dimensions NIM-standard double-width module (2.70 by
8.714 in.) per TID-20893 (Rev).
3. INSTALLATION
3.1. GENERAL INSTALLATION CONSIDERATIONS
The 414A contains no internal power supply but is used in
conjunction with a 401/402 Series Bin and Power Supply,
which is intended for rack mounting. Therefore, if vacuum
tube equipment is operated in the same rack, there must be
sufficient cooling air circulating to prevent any localized
heating of the all-transistor circuitry used throughout the
414A. The temperature of equipment mounted in racks can
easily
exceed
the
recommended
maximum
unless
precautions are taken; the 414A should not be subjected to
temperatures in excess of 120°F (50°C).
must be given to ensure that reflections in the driving
transmission cable do not occur.
There are three general methods of termination that are
used. The simplest of these is shunt termination at the
receiving end of the cable. A second method is series
termination at the sending end. The third is a combination
of series and shunt termination, where the cable impedance
is matched both in series at the sending end and in shunt at
the receiving end. The most effective method is the
combination, but termination by this method reduces the
amount of signal strength at the receiving end to 50% of
that which is available in the sending instrument.
3.2. CONNECTION TO POWER
Turn off the Bin power supply when inserting or removing
modules. The ORTEC 400 Series is designed so that it is
not possible to overload the Bin power supply with a full
complement of modules in the Bin. Since, however, this
may not be true when the Bin contains modules other than
those of ORTEC design, the Power Supply voltages should
be checked after the modules are inserted. The 401/402 has
test points on the Power Supply control panel to monitor
the dc voltages.
3.3. LOGIC INPUTS TO THE FAST COINCIDENCE
The input pulses to the Fast Coincidence unit may come
from any source of logic pulses. The input impedance of
the Fast Coincidence is greater than 3000f2, and some care
To use shunt termination at the receiving end of the cable,
connect the 1J2 output of the sending device through 93f2
cable to the input of the receiving instrument. Then use a
BNC tee connector to accept both the interconnecting
cable and a 100S2 resistive terminator at the input
connector of the receiving instrument. Since the input
impedance of the receiving instrument is normally 1000J2
or more, the effective instrument input impedance with the
100J2 terminator will be of the order of 93f2, and this
correctly matches the cable impedance.
For series termination, use the 93f2 output of the sending
instrument for the cable connection. Use Q3SI cable to
interconnect this into the input of the receiving instrument.
The 1000J2 (or more) normal input impedance at the input
connector represents an essentially open circuit, and the
series impedance in the sending instrument now provides
the proper termination for the cable.