AVTECH ELECTROSYSTEMS AVRQ-4-B, Инструкция по эксплуатации

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1) With the power off, install an appropriately-configured daughterboard and DUT,
as described in the previous sections.
2) Connect the SYNC output (on the front panel) to the external trigger input of the
oscilloscope using (user-supplied) coaxial cabling.
3) Connect the (user-supplied) Tektronix P5100 probe to the rear-panel HV PULSE
connector using the (user-supplied) Tektronix 013-0291-00 probe-to-BNC
adapter, or a similar arrangement.
4) With the DUT door closed, gently insert the Tektronix P6246 differential probe to
mate with the output header on the daughterboard. When using the differential
probe, install the probe so that the “-” side is on the left, and the “+” side is on the
right. Please note that the P6246 has a maximum differential input voltage range
of 7V. If higher values of VCC2 will be used, a different probe will be required.
5) Power-up the AVRQ-4-B and the oscilloscope.
Caution: The HV PULSE oscilloscope probe must be rated for operation at 2 kV
(pulsed) or higher. Factory tests are conducted using a Tektronix P5100 probe, which has
a 2.5 kV peak rating and a 1000:1 division ratio. (Remember to adjust the compensation
of the probe to match your oscilloscope input.)
INTER-CHANNEL INTERFERENCE
The test arrangements on the preceding pages show both the high-voltage pulse and the
logic output being measured on the oscilloscope at the same time.
In practice, better results are obtained if the logic waveform is measured with the high-
voltage probe disconnected from the “HV PULSE” output. Otherwise, some of the very-
fast, very-high-voltage signal may couple to the low-voltage logic input through parasitic
capacitances in the oscilloscope and its cabling. This sort of interference is typically quite
sensitive to the exact positioning of the probe cabling.
If you observe this sort of interference, measure the signals one at a time, and use the
memory-storage feature of your oscilloscope if you wish to record them on the same
waveform photo.
The two photos below show the difference that this can make. The photos show typical
“HV PULSE” waveforms with with AMP1 = +1.5 kV, and a daughterboard installed in the
socketing, but with no DUT installed in the DIP8 socket on the daughterboard. (The lower
waveform in each photo is the LOGIC OUT “A” output, with R2 = 1 kΩ. A small signal is
coupled through parasitic capacitance in the socketing.)
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