most sensitive position (1/1) sensitivity is 500mm/A (0.002A/mm).
The
nominal galvanometer resistance is 550 ohms.
(2) ON-OFF switch. This switches the galvanometer lamp only, and is
not in the galvanometer circuit. It is located on the front panel to the
left of the sensitivity switch.
(3) Zero controls.
Two mechanical zeros are available, a coarse
control mounted atop the galvanometer suspension, and a fine control on the
front panel to the right of the sensitivity switch.
The coarse control
should require no adjustment except, possibly, at the time of installation.
(4) Terminals.
Two binding posts are available at the rear of the
right-hand side of the cabinet for connection to the Model 9460A Nanovolt
Amplifier.
(5) Connectors. A two-pin female connector mounted on the left-hand
side of the Model 9461A provides lamp power for the Model 9460A Nanovolt
Amplifier.
b. Zero procedure (with Model 9460A Nanovolt Amplifier).
When used
with a Model 9460A Amplifier the galvanometer should first be mechanically
zeroed with the sensitivity switch set at 1/1000 (least sensitivity). Then,
with the sensitivity switch set at 1/1 (greatest sensitivity), the final
zero should be achieved with the electrical zero control on the amplifier.
If this sequence is not followed, the galvanometer zero will shift as the
galvanometer is switched through increasingly sensitive ranges.
CAUTION
1. The suspension clamping screw need not be engaged
if the galvanometer is hand-carried from one location
to another.
If it is to be shipped, however, the
suspension should be clamped.
2. The galvanometer mirror is surface-aluminized and
easily scratched. Should it become necessary to clean
the mirror, lightly brush the surface with a loosely-
held wad of lens tissue dipped in acetone, chemically
pure (CP) grade.
Learning Event 5:
DESCRIBE THE MODEL 9154B STANDARD CELL ENCLOSURE
1.
Functional description.
The Transvolt Transportable Standard Cell
Enclosure Model 9154R (fig 2-13) is a four-cell instrument that has been
specifically designed for maximum convenience as a completely transportable EMF
Transfer Standard. It is equipped with its own integral rechargeable battery,
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