Datapulse 101 - Page 25

Connect the 50 ohm, 2 watt (minimum) power termination to the
POS OUTPUT jack.
Adjust the POSITIVE AMPLITUDE control to any convenient
setting.
Turn the POWER switch ON.
Monitor the output at the terminating load on the real time
oscilloscope using a high impedance probe.
Use an oscilloscope to measure the repetition rate and verify
that it is l. 0 MHz (with a period of 1. 0 microseconds). If it is
not, R15 (the oscillator calibration potentiometer) should be
adjusted to the repetition rate indicated on the front panel by the
position of the selector (in this case 1.0 MHz). R15 is on the
circuit board in the front left corner under the repetition rate
control assembly, labeled OSC on the top and accessible from
the bottom as a screwdriver adjustment.
CAUTION
Be sure the REPETITION RATE
vernier is fully clockwise before
adjusting R15.
Turn the REPETITION RATE vernier fully counterclockwise
and note that the frequency goes down to less than 0. 1 MHz.
If it does not, recheck the adjustment setting from the previous
step.
NOTE
If it is not possible to set R15 cor-
rectly, the oscillator circuit is
probably malfunctional.
Turn
the
REPETITION
RATE
selector
to
0.
1
MHz
and
the
vernier
fully
clockwise.
Switch
the
PULSE
WIDTH
to
l.
0
us
and
use
the
oscilloscope
to
verify
that
the
repetition
rate
is
O.
1
MHz.
Turn
the
REPETITION
RATE
vernier
fully
counterclockwise
and
verify
that
the
frequency
is
less
than
10
KHz.
Set
the
REPETITION
RATE
selector
to
10
KHz
with
the
vernier
fully
clockwise
and
switch
the
PULSE
WIDTH
to
10
us.
Verify
that
the
repetition
rate
is
10
KHz
for
these
settings
and
less
than
0.
l
KHz
with
the
vernier
fully
counterclockwise.
Set
the
REPETITION
RATE
selector
to
l.
0
KHz
with
the
vernier
fully
clockwise
and
switch
the
PULSE
WIDTH
to
0.1
MS.
Verify
that
the
repetition
rate
is
l.
0
KHz
for
these
settings
and
less
than
0.
1
KHz
with
the
vernier
fully
counterclockwise.
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