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generator should not be triggered any longer, so
the time-base line should not be visible.
6. Triggering 50 Hz
— Set "TRIGG. SOURCE" (SK3) to 50 Hz and
"TRIGG. MODE" (SK1) to "L.F ".
— Apply a sine-wave voltage with the mains fre-
quency to the Y-plug-in unit.
— After correct adjustment of "LEVEL" (R2), the
time-base generator should be triggered by an
internal voltage with the mains frequency.
— It should be possible to shift the starting point of
the time-base line across the sine-wave by means
of control "50 Hz PHASE" of the basic oscil-
loscope.
7. Time co-efficients
To adjust the time co-efficients, trimmers C33 and
C36, which are located on the left-hand side of the
unit, should be adjusted.
To gain access to these trimmers, the unit to be
measured should be connected to the basic oscil-
loscope via the extension plug.
— Set the below mentioned knobs to the following
positions:
UNIT PM 3347
"TIME/cm" (SK4) to " 20 µsec./cm".
"LENGTH" (R1) clockwise.
BASIC OSCILLOSCOPE
"Magnifier" to "X 1".
— Apply atime-marker signal with a time interval of
20 µsec. to a Y-plug in unit (PM 3333).
Adjust "LEVEL" (R2) for a triggered display and,
with C36, adjust the time co-efficient so that 8
periods have a width of 8 cm; tolerance 1 0 /0•
Measure the time co-efficient across 8 cm (sym-
metrical around the centre of the screen).
Change the time interval to .2 msec. and set
"TIME/cm" (SK4) to ".2 msec.".
Adjust "LEVEL" (R2) for a triggered display and
with C33 adjust the time co-efficient so, that 8
periods have a width of 8 cm; tolerance 1 0 /0.
Check the time co-efficients in all not yet men-
tioned positions of "TIME/cm" (SK4). Select the
time marker signals so that they correspond with
the time co-efficient selected with "TIME/cm"
(SK4).
Measure the time co-efficient across 8 periods; the
periods should have a width of 8 cm; tolerance
2 1/4 ~/0.
8. Sweep length
— With "LENGTH" (R1) turned fully clockwise
check the length of the time-base line. In all posi-
tions of "TIME/cm" (SK4), the time-base line
should be longer than 10 cm. If necessary, select a
different value for R102.
— With "LENGTH" (R1) turned fully anti-clockwise
and "TIME/cm" (SK4) to "1 msec./cm", the length
of the time-base line should not exceed 4 cm.
C.
DELAY
Before carrying out this measurement, it is necessary
to check that the time co-efficients are correctly
adjusted (see point B7).
The delay is adjusted by means of the adjusting
potentiometers "MIN. DELAY" (R132) and "MAX.
DELAY" (R129).
These potentiometers are found on the left-hand side
of the plug-in unit. To gain access to the potentio-
meters, the unit to be measured should be connected
to the basic oscilloscope via the extension plug.
1. Adjustment of the counter knob "Delay-time
multiplier"
— Turn knob "DELAY-TIME MULTIPLIER" (R4)
fully anti-clockwise and check that the counter
indicates 0.00 in this position.
— If it should be necessary to readjust the knob, it can
be unscrewed by means of the small key which is
found behind the frontplate (see Fig. 23).
— Turn the shaft of R4 fully anti-clockwise.
— Replace the counter knob on the shaft and tighten
the knob by means of the fixing screw.
2. Min. delay and max. delay
— Set the below mentioned knobs to the following
positions:
UNIT PM 3347
"TRIGG. MODE" (SKl) to "AUT."
"TRIGG. SLOPE" (SK2) to "~-"
"TRIGG. SOURCE" (SK3) to "INT."
"DELAY TIME" (SK4) to ".2 msec."
"DEL'D TRIGG." (SK6) to "STARTS A"
"DEFLECTION" (SK7) to "B INTENSIFIED BY
A"
"LENGTH" (R1) fully clockwise
"DELAY-TIME MULTIPLIER" (R4) to "2.00"
BASIC OSCILLOSCOPE PM 3330
"TRIGG. MODE" to "H.F."
"TIME/cm" to ".5 µsec./cm"
"X-DEFLECTION" to "X-UNIT"
"MAGNIFIER'" to "X 1"
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