Ballantine 1620A, Инструкция по эксплуатации

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7-11
SECTION 7A
7A-1. OPTION 30
7A-2. OPTION 30 represents an
improvement introduced to compensate for
the thermal drift due to the material of the
shunts on the 20A and 100A scales.
Normal shunt material can produce a drift of
up to
±
2500 ppm and requires a long time
(approximately 15 minutes) for the unit to
stabilize at high currents.
By introducing thermisters attached to the
shunts with a network of resistors selected
at test, the thermal
drift is reduced to less than
±
250 ppm
(typical drift is less than
±
100 ppm). This
will insure that the amplifier can be used at
its full capacity within less than a minute and
eliminates the need for stabilization time at
high currents (on the 20A and 100A scales).
The following figure represents the electrical
schematic of the Option 30 (thermal
compensation).
Figure 7A-1. Model 1620A, Option 30 Schematic Diagram
PARTS LIST FOR OPTION 30 , MODEL 1620A
SCHEMATIC
REF.
BALLANTINE
PART NO.
DESCRIPTION MANUFACTURER
PART NO.
R-TH1
R-TH2
R-SER1
R-SER2 27-10035-0
27-10035-0
TBD
TBD THERMISTER, 1KOHM
THERMISTER, 1KOHM
RESISTOR, 1/4W, 1%, SEL. AT TEST
RESISTOR, 1/4W, 1%, SEL. AT TEST NT05-10291
NT05-10291
TBD
TBD
R51
50
R-TH1
1k
*C18
.033
*R50
51.1
2A CAL
*R56
46.4
*R54
3K
NOTE: RESISTORS MARKED WITH "*" TO BE SELECTED AT TEST
*R-ser2
(sel. at test)
R55
50
A
2
1
B
C
20A CAL
TO K8-5
*R-ser1
(sel. at test)
R58
1.96K
R57
10
R-TH2
1k
R49
1.33K
*R53
3K
R52
10