Five resistors are connected in parallel and are, in
turn, connected in series with the lamp. These resistors
limit the current at starting and during operation, and
supply the correct electrical values to the lamp.
12-INCH MODIFIED MERCURY-
Some of the older mercury-xenon searchlights are
12-inch, incandescent lamp searchlights converted to
use a 1,000-watt, compact, mercury-xenon arc lamp
(fig. 2-2). The addition of a small amount of mercury
to xenon in a gaseous discharge arc lamp produces a
much more brilliant light with a great deal of radiation
in the green and ultraviolet parts of the spectrum. The
increase in light intensity greatly increases the range
of the searchlights.
The modifications made to convert the searchlight
include the installation of a lamp holder, lamp adjuster
assembly, and lamp starter assembly mounted on the
Other modifications include the following:
1. Providing a 115-volt, 60-Hz ballast unit to be
mounted below the deck near the searchlight and
connected to it by a flexible cable.
2. Installing the short-arc mercury-xenon lamp.
3. Furnishing the additional onboard repair parts
necessitated by the changes. (The electrical components
include a ballast, transformers, capacitors, spark gaps,
and switch circuits.)
Figure 2-2 .12-inch modified mercury-xenon arc searchlight.