3
discriminator threshold from 0.05V to 10.05V above signal will be completed before converter reset is
the Lower-Level (T) setting . initiated. Factory-set in the positive input position.
SCA LOWER LEVEL (T)
Ten-turn precision locking
potentiometer sets the SCA lower-level
discriminator threshold from 0.05V to 10.05V.
TAC INHIBIT
Two-position locking toggle switch. In
the Inhibit position the TAC output is available only
if the output amplitude is within the SCA window. In
the Out position, the SCA has no effect on the TAC
output.
2.3. REAR PANEL CONTROLS
EXT STROBE RESET
Two-position locking toggle
switch allows the converter to be reset nominally
10 µs or 100 µs after an accepted Stop input signal
if an Ext Strobe signal has not been received.
2.4. INPUTS
All six front panel inputs listed below are dc-
coupled, edge-triggered, and PWB jumper-
selectable to accept either negative or positive
NIM-standard signals. Input impedance is 50
in
the negative position and >1 k
in the positive
position. The threshold is ~-400 mV in the negative
and ~+2 V in the positive position.
STROBE
Front panel BNC connector provides an
external means to strobe a valid output signal from
the TAC in the Ext Strobe mode. The input signal,
exceeding threshold within the Ext Strobe Reset
interval after the Stop input, initiates the read cycle
for the linear gate to the TAC output. Factory-set in
the positive input position. Ext Strobe Reset interval
has minimum value of ~ 0.5 µs and a maximum
value of nominally 10 µs or 100 µs Switch-
selectable on rear panel.
START
Time conversion initiated when Start input
signal exceeds threshold. Factory-set in negative
input position.
STOP
Time conversion terminated when Stop input
signal exceeds threshold. Factory-set in negative
input position.
RESET/INHIB
Terminates conversion cycle and
maintains reset condition, inhibiting further TAC
conversions for the duration of the reset cycle or
the Reset/Inhib pulse, whichever is longer. A TAC
Rise Time
50 ns.
output pulse in process at the time of Reset/Inhib
START GATE
Provides an external means of
gating the Start circuitry in either Coincidence or
Anticoincidence with the Start input signal. Start
Gate input signal must cross threshold
{
10 ns prior
to the Start input signal and overlap the trigger
edge of the signal. Factory-set in the positive input
position.
STOP GATE
Provides an external means of gating
the Stop circuitry in either Coincidence or
Anticoincidence with the Stop input signal. Stop
Gate input signal must cross threshold
10 ns prior
to the Stop input signal and overlap the trigger edge
of the signal. Factory-set in the positive input
position.
2.5. OUTPUTS
TAC
Front and rear panel BNC connectors provide
unipolar pulse.
Amplitude
0V to +10V proportional to Start/Stop
input time difference.
Time
End of delay period in Int Strobe mode;
prompt with Strobe input in Ext strobe mode.
Width
Adjustable by PWB potentiometer from 1 µs
to 3 µs.
Impedance
Front panel Z, <10
; rear panel 93
.
Rise Time
~250 ns.
Fall Time
~250 ns
VALID START
Rear panel BNC connector provides
NIM-standard slow-positive logic level signal.
Amplitude
Nominally +5V. Complement signal
selectable by PWB jumper.
Time and Width
From accepted Start input to end
of reset.
Impedance
Z
z
10
.
Rise Time
50 ns
Fall Time
50 ns
VALID CONV
Rear panel BNC connector provides
NIM-standard slow-positive logic level signal to
indicate a Valid Conversion.
Amplitude
Nominally +5V. Complement signal
selectable by PWB jumper.
Time and Width
From end of internal delay after
Stop to end of reset.
Impedance
Z
10
.
Fall Time
50 ns.
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