5911 tuning adjustments must be readily accessible
and reeuire only a small screwdriver or tunin6 wrench for ad-
justment. No detuninZ shall result when cover is placed on
transmitter. separate metering; must be provided for each stage.
All component parts shall be mounted so as to withstand
constant jar and vibration. All heavy parts shall be firmly
mounted on the chassis. In as far as possible all small con-
densers, resistors, etc. shall be mounted on terminal strips,
and not be dependent on leads for mechanical support.
A control head shall be ;rovided ,shish shall Nave
microphone plu,, receiver volume and squelch, and indicating
pilot 11k -ht.
Transmitters shall be sup lied complete with microphone,
antenna, cables, and all necessary hardware for complete installa-
tion at the unit price bid.
9ntennas shall be designed for roof ton mounting, with
a stainless steel whin. They shall have adequate insulation and
support and be of such design that they will not normally be
damaEed by striking foreign objects while the car is in motion.
It shall provide water tight mountin &, and it shall be
possible to replace the whip when necessary. A flexible coaxial
line shall be provided, together vd th all necessary cou- )lings.
The impedance of the line shall be such that a standing
wave ratio of two to one, or less, is realized. Insulation in
the coaxial line shall be solid low loss type.
All transmitters shall have all spurs ,)us radiations
reduced to a minimum of 60 decibels.
MOBILE RECEIVERS FOR
AUTOMOBILESAND_F_I_RE
PUMPERS � Receivers shall be designed to operate on
155.61 megacycles with a frequency modula-
tion of plus or minus twenty kilocycles.
5-