3.5.8 Siren. When specified (see 6.2), a low frequency type siren shall be installed outside
the vehicle or between the grille and the radiator. The siren shall have a chrome or enamel finish.
A gasket not less than 1/16-inch thick shall be installed between the siren mounting bracket and
the vehicle to minimize drumming. Reinforcement shall be provided, when needed, at the point
of attachment. The siren location shall permit servicing of the vehicle without removing the
188.8.131.52 Dual siren controls. The siren shall be capable of being actuated by both a foot
operated switch and the standard horn actuator. A separate dash mounted switch, for driver
preselection of horn or siren operation, shall be provided. Switch positions shall be identified.
3.5.9 Electronic siren, public address and radio amplifier system. When specified (see 6.2),
an electronic siren system with selector controls for siren, public address and radio amplification
through an external speaker shall be provided. The system shall be a Federal PA-20A,
Dietz 14-450, or Unity SPR73 Model or equivalent. The system shall have a sound intensity of
not less than 98 decibels at a distance of 100 feet from the speaker, using a reference pressure of
0.0002 microbar. The amplifier and its controls shall be installed inside the vehicle in a location
accessible to the driver and to the assistant driver. A microphone of the magnetic noise canceling
type, connected by a coiled core, shall be provided and located in a position convenient for use
by both the driver and the assistant driver. Microphone stowage shall be provided on the
instrument panel. The system shall permit the broadcasting of routine and emergency radio
announcements from an on board vehicle radio to be installed by the Government. A two-way
radio audio tap cable, permitting incoming two-way radio messages to be rebroadcast through the
public address system, shall be furnished. Dual siren controls (see 184.108.40.206) shall be provided.
The amplifier unit shall include volume control and selection of "Radio," "P.A.," and
"Siren mode." Siren mode controls shall include "Manual," "Yelp," "Wail," and "Hi-Lo"
220.127.116.11 Speaker. An external weatherproof speaker shall be installed on the centerline of the
cab roof or above the front bumper to the rear of the brushguard. Cab roof installation shall be in
a location that will not obstruct light from or movement of the roof mounted spotlight. The
speaker, when roof mounted, shall be of the low silhouette type, designed for roof mounting.
The speaker shall be of metal with a chrome finish or of fiberglass painted to match the vehicle
exterior color. A gasket not less than 1/16 inch thick shall be furnished between the speaker
mounting bracket and the vehicle to minimize drumming. Reinforcements shall be provided on
the vehicle at the point of attachment of the speaker. The speaker location shall permit servicing
of the vehicle without removing the speaker.