transmitter and amplifier units should be installed in a light, well ven-
tilated room and so situated as to provide easy access to the antenna and
ground connections. At least three feet of clearance should be allowed on
all sides and top of the units. If forced ventilation of the transmitter
room is employed, care should be exercised in arranging this ventilation
so that dust and dirt are not blown or drawn into the equipment.
Two hardwood bases should be prepared for the units in accordance
with the installation drawing, and if practicable, all ground leads, power
and audio conduits should be in place before the equipment is set up. The
No. 12B Radio Transmitter should be placed on one of the hardwood bases
and the back and two sides of the unit should be removed by removing the
screws which fasten them to the frame. The right side of the transmitter
unit is removed permanently and side guide pins at the top of the trans-
mitter frame should be removed to permit the proper alignment of the
transmitter and amplifier units.
Before the No. 71B Amplifier is set in place on its hardwood base,
remove the knock-outs in the junction box in the No. 12B Radio Trans-
mitter. This junction box is located in the lower front right-hand corner
of the transmitter unit (see view "C-C" on installation drawing ESX-
601752). Remove the back and the right side from the amplifier unit by
removing the screws which fasten them to the frame. The left side of the
unit should not be removed. When the amplifier unit is in place and care-
fully aligned with the transmitter unit, a 11/2 inch Chase nipple and lock-
nut should join the junction box in the transmitter unit to the amplifier
unit.
Ground System
A typical interior ground system layout is shown on the installation
drawing (ESR-601783). All metal structures such as building frame,
water and steam pipes, conduits, roofs and stacks should be bonded to the
interior ground system. All ground connections should be as short and
direct as possible and all joints should be soldered or welded. Where in-
stallations are made in tall buildings the information given on ESR-601783
and associated drawings may not apply entirely, in which case additional
engineering information should be requested.
The main ground terminal of the transmitter unit is located at the
extreme lower right-hand corner in front of the junction box. It consists
of a cadmium plated copper strip 43/4 inches long which is fastened to the
main transmitter frame by means of two bolts located at the ends of the
strip. The main ground terminal of the amplifier unit is located at the
extreme lower left-hand corner of the cabinet in front of the terminal
strip. It is similar in construction to that of the transmitter unit and is
fastened to the main frame of the amplifier by means of bolts. The ground
connection for each unit should consist of a 4 inch by 1/64 inch copper
strip, one end of which should be soldered to the removable strip which is
then bolted to the ground terminal. The other end is soldered to the main
ground system. It is suggested that the lugs which are bolted to the
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