Tektronix 549 Instruction Manual page 118

F ig . 6 - 4 7 , M e a s u r in g C R T b e a m c u r r e n t .
2. Depress both ERASE buttons to prepare the target
area (or storage,
3. W rite 3 or more lines per cm an (he target aroa by
depressing the N O RM -SIN G LE SW EEP switch to RESET.
After each line is written, change the vertical position of
the spot before writing the next trace,
4. Carefully check the written lines visually for breaks
or gaps, If no breaks or gaps are evident after 10 seconds,
adjust the Backplate Level to reduce the operating voltage
by 5 volts,
5. Erase twice, wait 1 0 seconds then write again and
check for breaks or gaps.
6. Repeat this procedure of decreasing the operating
voltage level in 5 volt steps until breaks of approxi­
mately 0.025 inches occur. This is the writing threshold.
F ig . 6 -4 8 W riting lim it*.
Record this operating voltage point and return the voltage
to its original level,
N O T E
Do not change the IN T E N S IT Y , FO C U S or A S TIG
control settings.
g. Upper W ritin g Limit is found as follows:
operating voltage in 5 volt steps.
stored lin e s between each step for indications o f fade-up.
The operating voltage which produces a trace spread of
0.025 inches greater than its normal width, or a background
spot greater than 0.025 inches which becomes as bright as
the written area, is the upper writing limit.
voltage.
Calibration— Type 549
Raise the
Carefully observe the
Record this
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