4Bids will be accepted on mobile units between 7
watts and 30 watts of power. Power, ease of service, and
mounting will be considered as well as price in the selection
of equipment. Transmitters shF11 be designed to operate from
a standard 6 volt automobile battery. Mechanicpl construction
shall insure against premature failure due to vibration, shall
afford ease of service and provide protection from dirt and
from articles that may be carri °d in trunk compartment of an
automobile.
Transmitters shall use phase shift modulation. A
deviation of five is to be maintained. A frequency swing of
plus or minus 20 kilocycles shall constitute 100 :per -cent
modulation. Pre - emphasis giving a logarithmic increrse of ten
decibels from five hundred to three thousand cycles shali be
uaed.
Complete twenty kilocycle modulation shall be real-
ized by speaking in a normal voice one inch from the microphone.
Limiter notion shall prevent overswin6 on loud voices. Means
for controlling and testing the transmitter shall be available
with the normal test equipment used at the transmitter proper,
for the puroose of alignment.
Transmitters shall have heswy metal dust covers,
mountings plates etc., which shall _provide complete protection
from dirt, water or mechenicnl damage. The transmitters shall
be constructed on a heavy guage welded steel chassis, co)per
or cadmium plated. The transmitter shall be easily removable,
without tools, for service and adjustment.
All plugs and cable connectors shall be heavy type
metal enclosed with sere- type retaining rings which prohibit
accidentally jarring loose. Plugs shall be designed so that
no "A" battery voltage is exposed. Battery cables shall be
heavy guage wire to minimize voltage drop. Battery lead must
be fused near "hot" battery conn�c tions.
4-