1720/1721
3–1
Section 3
Installation
The shipping carton and pads provide protection for the instrument during
transit, they should be retained in case subsequent shipment becomes necessary.
Repackaging instructions can be found in Section 6 (Maintenance) of this
manual.
Electrical Installation
This instrument is intended to operate from a single-phase power source with
one current-carrying conductor at or near earth-ground (the neutral conductor).
Only the Line conductor is fused for over-current protection. Systems that have
both current-carrying conductors live with respect to ground (such as phase-to-
phase in multiphase systems) are not recommended as power sources.
All members of the 1700-Series instrument line operate over a frequency range
of 48 to 66 Hz, at any mains voltage between 90 Vac and 250 Vac. These newer
versions of the 1730-Series instruments do not require any internal changes to
select their operating voltage range.
Not all installations are identical. In order to make operation of the 1720/1721
Vectorscope as flexible as possible there are internal jumpers that can be changed
to provide operating flexibility. For example, it is possible to select CW
Subcarrier for EXT REF instead of Composite Video or Black Burst. The
factory preset position is indicated by a box printed on the etched circuit board.
Table 3–1 details these internal jumper selections. Be sure that all operators are
aware of changes, to prevent unnecessary trouble reports, if any of these jumpers
are placed in the optional position. See Figure 3-1 for location of the internal
plug jumpers.
The rear-panel XY INPUT connector is a 15-pin, sub-miniature, D-type
connector that provides input to the Horizontal and Vertical (X and Y) Amplifi-
ers. They are balanced (differential), dc-coupled, high impedance (>20 kΩ),
unterminated inputs provided for audio applications. If ac coupling is desired,
external capacitors are required. These inputs are factory calibrated for 0 dBm in
600Ω but can be adjusted for any 600Ω system between 0 and 12 dBm. See
Figure 3-2.
Packaging
Power Source
Mains Frequency and
Voltage Ranges
Operating Options
X Y INPUT Connector
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