Submarine Hull Is "Mike" - AmericanRadioHistory.Com

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552
1932 PRICE GUIDE
Radio Supplies- Tubes -Sets
Every item you require in your business is
in this book, from the finest high grade
mike to the smallest screw.
GUARANTEED QUALITY GOODS
Prices Lowest Erer Quoted
Fresh new dependable Merchandise at
Bargain Prices!
Leading Manufacturers Lines Complete
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SAMPLE BUYS FROM THIS BOOK
$14.65 $1.98 69c
4Tube Replacement 500V -8Mf
Receiver Transformer Dry Cond.
and Three Thousand Other Bargains
HEADQUARTERS
for SERVICE MEN'S SUPPLIES
RaJolek Co.,
103
Canal Station
Chicago, Ill.
Please send me without obligation
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Electrolytic
Condensers
Conservative voltage ratings,
fastest reforming, lowest leakage
factor, minimum noise,
exceptionally low power factor,
most effective filtering.
longest service life - these
features characterize Dubilier
Electrolytic Condensers.
RADIO -CRAFT March, 1932
"SUB" HULL IS "MIKE"- REPRODUCER
hull of the submarine but should he separated
by a thin wall of water. For this
reason, the diaphragms are clamped on the
reproducer by capped screws which project
one -quarter inch from the surface and not
by flat -headed screws. An external view
of the re- producer is shown in Fig. I) and
an internal view showing all component
parts, appears in Fig. E.
Description of Apparatus
(Continued from page 521)
The apparatus consists of a model MG
underwater reproducer, including the type
SE 3489 under -sea reproducer and SE 3488
power amplifier with auxiliary batteries, announcing
microphone, telephones and cable
equipment. The reproducer is essentially
an electrodynamic speaker of novel design,
employing the use of two parallel diaphragms
connected by a tube as an armature.
These diaphragms are only .070-in.
thick and are accurately machined front
bronze metal to the end that they be noncorrosive
and non -magnetic. The other component
parts of the magnetic speaker are
the iron magnetic casing or pole pieces,
D.C. field coil and core with the A.C. coil,
or speaking coil, wound thereon.
The design and arrangement of the parts
are such as to withstand external hydrostatic
pressures up to 150 pounds per square
inch. This arrangement of the parts necessitates
much care in the machining of them
and their assembly. The machined dimensions
of the depths of the brass casting and
the diaphragms must equal the length of
the armature tube. So, if the rubber gaskets
maintaining water -tightness are too
thick, preventing the parts coning together,
there will be lost motion between the armature
tube and the diaphragm. ii. .1uch care
is given this feature so the operation of the
s )taker will not stiffer interference by
grounds or short circuits that would be
cunset' by salt water in the reproducer.
The type SE :1488 transmitter-receiver,
the diagram of which is shown in Fig. 1,
includes in its essentials one two -stage receiver-
amplifier and one four -stage power
amplifier having a push -pull output stage.
'l'he large 48 -volt storage battery supplies
a fi -volt supply to the filaments of the SE
4374 (l'X 201A) tubes and the talking microphone,
and a 10 -volt supply to the
filaments of the l'X 250 and SF, 2566 (CX
210) tubes. 'l'he remaining group of batteries
supplies 38 volts to the motor end
of a dynamotor through the relay contacts.
Fig. D
Close -op view of the magnetic unit.
The coils of the SE 1914 relays are energized
front 20 volts through the "press -totalk"
switch in the handle of the microphone.
'l'he 90 -volt supply for the plaste voltage
to the type SE 4:374 (l'X 201:1) tubes is
obtained front self- contained type SP. :35:35
"11" batteries. A 90 -volt negative grid bias
for the 1-X 250 and :35-volt grid bias to the
SE 2566 (l'X 2111) tubes is supplied from
"Ii" batteries used as "C"
type SF. :1535
batteries. A negative 4//-. -volt bias for the
type SE 4:374 (l'X 201:\) tubes is obtained
from a small 41ß_- colt "C" battery.
e
Available in upright or
inverted aluminum cans,
and in cardboard containers
with lug or wire
lead terminals. In single
and multiple section
units, and in capacities
up to 20 mfd., for high
and for low D. C. voltages.
Write for Catalog 121
describing Dubilier electrolytic
condensers as
well as paper, mica and
other dielectric condensers
for all purpose,
Dubilier
Condenser Corporation
New York City
4377 Bronx Blvd.
Fig. 1
Schematic diagram of the apparatus
aboard the rescue vessel. The "mike" -
reproducer is shown at the lower left
and is lowered to the stricken "sub."
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