the 'red' Infraphil
The oldest Infraphil heat lamps with type
number 7525 were made of matted
transparant glass. It's successors with
type numbers 7526 and 7529 had a red
filter integrated in the glass and in the
documentation they were frequently
referred to as "the red Infraphil". Like all
Infraphil lamps, both white and red types
were equipped with an internal reflector.
The red filter did not influence the yield of
infrared radiation but it restrained the
bright visual light, preventing the need for
protective glasses.
The leading part of the type number of early Infraphil heat lamps equaled that of the
type number of the armatures they came in. The type number was printed on the front
of the lamp, together with the operation voltage, the power dissipation (always
150W), a production code, the country of origin, the Philips trademark and an Infraphil
logo consisting of a rectangle with rounded corners with the brand name infraphil in
it. On the first letter i of infraphil was an eight-pointed star that partly sticked out of
the rectangle. The production code was formed from a combination of small points
and stripes in a fixed configuration.