AVTECH ELECTROSYSTEMS AVRK-3-B, Instructions Manual

Page: 23 / 43

WARNING: The output stage may be damaged if triggered by an external signal at a
pulse repetition frequency greater than 1 kHz.
GATING MODES
Triggering can be suppressed by a TTL-level signal on the rear-panel GATE connector.
The instrument can be set to stop triggering when this input high or low, using the front-
panel gate menu or the appropriate programming commands. When gated, the output
will complete the full pulse width if the output is high, and then stop triggering. Pulses
are not truncated.
PULSE WIDTH CONTROL
The pulse width can be varied from < 6 ns to > 35 ns using the front-panel controls or
by computer command.
The pulse width circuitry has a thermal settling time of several minutes. The pulse width
may drift noticeably over this time, until thermal equilibrium is reached. This is
particularly noticeable at wide pulse widths.
Also, the pulse width tends to increase as the amplitude is reduced, especially at wide
pulse widths.
For these reasons, the pulse width settings should not be relied upon for any degree of
accuracy. Verify the actual output characteristics by measuring the main output or the
monitor output on an oscilloscope.
MONITOR OUTPUT
The user can non-invasively measure the output amplitude and pulse width by
attaching a high-quality 50 Ohm load to the rear-panel monitor output connector. The
output waveform on this BNC connector is attenuated by a factor of 10 compared to the
voltage on the main output connector.
AMPLITUDE DYNAMIC RANGE
Avtech high-speed pulse generators are optimized to operate near their maximum rated
amplitude. Generally, operation below 20% of the maximum rated amplitude is not
recommended. To generate pulses below this level, the pulse generator should be
operated near its maximum rated amplitude, and one or more coaxial attenuators
should be connected to the output.
23