HP 3478A Technical Manual page 45

3478A 3478A
stant is then calculated and stored into the Calibration stant is then calculated and stored into the Calibration
RAM. RAM. The constant is used The constant is used to calculate
readings. readings.
4-80. Calibrating 4-80. Calibrating the the 3478A 3478A
4-81. The 3478A is calibr 4-81. The 3478A is calibrated by
input (INPUT Terminals shorted) and then applying a full input (INPUT Terminals shorted) and then applying a full
scale input (or in scale input (or in some cases a some cases a 1/3 scale
example on how calibration is performed is in the example on how calibration is performed is in the
following steps. following steps. The The calibration
Function's Function's 3V Range 3V Range is chosen is chosen for the
ranges and ranges and functions are functions are similar.
through the example before using the calibration through the example before using the calibration
procedures, to gain an understanding of how the 3478A procedures, to gain an understanding of how the 3478A
is calibrated. is calibrated.
a. a. Set the 3478 Set the 3478A to the A to the DC Volts Function an
Range. Range. Make sure the Make sure the instrument is not instrument is not in Autorange.
b. b. Short the in Short the instrument's HI strument's HI and LO INPUT Terminals
(zero input). (zero input).
c. c. Using a small Using a small flat blade flat blade screwdriver,
panel CAL ENABLE Switch to the calibration enable panel CAL ENABLE Switch to the calibration enable
position (the slot of the switch is in the vertical position, position (the slot of the switch is in the vertical position,
as shown on the front panel). as shown on the front panel).
d. d. Set the Set the multimeter to multimeter to the Single
pressing the SGL/TRIG button. pressing the SGL/TRIG button.
e. e. A zero A zero reading, or reading, or an approximate
should now be displayed. should now be display ed. In addition to t
is also displayed to the right of the reading (e.g. " + is also displayed to the right of the reading (e.g. " +
0.00002C:"). 0.00002C:").
f. f. Press the Press the blue Shift blue Shift button
(CAL) button. (CAL) button.
g. g. The 3478A The 3478A then then makes a
decides what type of input is applied to the instrument. decides what type of input is applied to the instrument.
Since it is a zero input, the 3478A should now display + Since it is a zero input, the 3478A should now display +
0.00000? VDC. 0.00000? VDC. (The displayed "C:" (The display
",?".) ",?".)
h. h. Press the Press the SGL/TRIG (Single SGL/TRIG (Single Trigger) butt
once. once.
i. i. The 3478A The 3478A will display will display "CALIBRATING"
five seconds and then "CAL FINISHED" for about two five seconds and then "CAL FINISHED" for about two
seconds. seconds. The zero The zero calibration const calibration constant for the
Function in the 3V Range is now stored in the Function in the 3V Range is now stored in the
instrument's Calibration RAM. instrument's Calibration RAM.
j. j. Remove the Remove the short short from
accurate + accurate + 3V to t 3V to the HI and he HI and LO INPUT Terminals.
best accuracy, use a + best accuracy, use a + 3V calibration source of which its
exact value is known (e.g. + exact value is known (e.g. +3.00015V, +3.00005V, etc.).
k. k. Press the Press the blue Shift blue Shift button a
to calculate the cor the correct
ated by first applyi first applying a zer ng a zero o
1/3 scale input). input). An
calibration of of the the DC DC Volts
for the example. example. Other
similar. It is sug It is suggested to gested to go
DC Volts Function and the 3V
in Autorange.
and LO INPUT Terminals
screwdriver, set the fro set the front nt
the Single Trigger mode by Trigger mode by
an approximate zero reading zero reading, ,
In addition to the reading, "C:" he reading, "C:"
button and then and then the LOCAL the LOCAL
makes a measurement measurement and
ed "C:" is replaced is replaced by a
Trigger) button only
"CALIBRATING" for about
ant for the DC Volts
from the the 3478A 3478A and and apply
LO INPUT Terminals. For
3V calibration source of which its
3.00015V, +3.00005V, etc.).
button and then nd then the LOCAL the LOCAL
(CAL) button. (CAL) button.
rect
l. l. The 3478A The 3478A again makes a
time decides time decides that the
should now should now show "+
voltage is another value, like + IV for example, the voltage is another value, like + IV for example, the
display will show the other value (" + display will show the other value (" + 1.00000? VDC").
An m. m.
unknown, but the source is accurate enough to calibrate unknown, but the source is accurate enough to calibrate
Volts the multimeter, continue with step o. the multimeter, continue with step o.
Other
go n. n. If the exact value of t If the exact value of the calibration source is known,
the 3478A can be ca the 3478A
only thing to remember is that the input value cannot only thing to remember is that the input value cannot
deviate from the absolute full scale (or 1/3 scale) value deviate from the absolute full scale (or 1/3 scale) value
by more than by more than + 7%.
d the 3V follows: follows:
1. 1. After the CAL After the CAL button is p
has decided that the applied voltage is within + has decided that the applied voltage is within +
7%o of +3V, the instrument displays "+3.00000? 7%o of +3V, the instrument displays "+3.00000?
VDC". VDC".
changed using the Uprange and Downrange changed using the Uprange and Downrange
buttons until the applied value and displayed value buttons until the applied value and displayed value
agree with each other. agree with each other.
2. 2. If the source is abov If the source is above + 3V, press the 3
Uprange button until the displayed reading agrees Uprange button until the displayed reading agrees
with the with
increment the reading by one count. To continue increment the reading by one count. To continue
increasing the displayed reading, press the button increasing the displayed reading, press the button
repeatedly. repeatedly.
3.00015V, press the Uprange button 15 times, until 3.00015V, press the Uprange button 15 times, until
"+3.00015? VDC" is display "+3.00015? VD
pressed too long and the displayed reading is too pressed too long and the displayed reading is too
high, press the Downrange button until the values high, press the Downrange button until the values
agree. agree.
and 3. 3. If the source is b If the source is below +3V, press
Downrange button until the displayed reading Downrange button until the displayed reading
agrees with agrees
by a same as using the Uprange button, except the same as using the Uprange button, except the
displayed reading is decreased rather than displayed reading is decreased rather than
increased. increased.
on only 2.99985V, press the Downrange button until 2.99985V, press the Downrange button until
"+2.99985? VDC" is displayed. "+2.99985? VDC" is displayed.
for about o. o. Press the Press the SGL/TRIG button
DC Volts p. p. The 3478A The 3478A will display
five seconds and then "CAL FINISHED" for about two five seconds and then "CAL FINISHED" for about two
seconds. seconds. The 3V calibratio
the 3V Range in the DC Volts Function is now stored in the 3V Range in the DC Volts Function is now stored in
apply an an the instrument's memory. the instrument's memory.
For
q. q. If no more calibr
3478A's CAL ENABLE switch to the horizontal position. 3478A's CAL ENABLE switch to the horizontal position.
The instrument is now ready for use. The instrument is now ready for use.
4-12 4-12
again makes a measurement, and
that the applied input applied input is + 3V.
show "+ 3.00000? 3.00000? VDC".
If the If the exact value exact value of the of the calibration sou
he calibration source is known,
can be calibrated to librated to that known
+ 7%. The calibration The calibration is performed as
button is pressed and the 3478A
The reading The reading on the on the display
e + 3V, press the 3478A's
the source. source. Pressing the butt Pressing th
For example, For example, if if the
C" is displayed.
elow +3V, press the 3478A's
with the the source. source.
For For example, example, if if the
SGL/TRIG button only once.
will display "CALIBRATING" for
The 3V calibration constant n constant (gain constant)
If no more calibration is to ation is to be performed, set
TM 11-6625-3071-14 TM 11-6625-3071-14
measurement, and this this
is + 3V. The display The display
VDC". If the applied If the applied
1.00000? VDC").
calibration source is rce is
that known value. value. The The
is performed as
ressed and the 3478A
display can now can now be be
478A's
e button once on once will will
the source source is + is +
ed. If the If the button w button was as
the 3478A's
This opera This operation tion is the is the
the source source is is + +
only once.
"CALIBRATING" for about about
(gain constant) for
be performed, set the
for
the