The Bridgeport times and evening farmer., 1922-04-24


dilecto supported and held away
from the panel board by eight coil
springs, stuffed with cotton. This
arrangement effectively supports
the two vacuum tubes and elm
mates all noise" by a spring sup
port system that has a high damp
'ng, thus quickly eliminating vlbra-
ton. The leads from the vacuum
tube receptacles are brought out
t. binding posts on small strip
terminal board which has engraved
upon it an indentifying letter for
each terminal. The grid terminal
is usually marked &c" the plate
terminal is marked "P," and fl
ament terminals respectively Z and
At the left of the panel board
are two "input" binding posts and
at the right are the telephone"
binding posts. At the bottom of
the panel are three binding posts
for connecting the six-volt filament
and the A0-volt plate batteries.
The middle post is common to both
each tube rs automatically con-
trolled BY it's filament -heostat.
Vacuum Tube Sets Proper.
Under this caption, the wonder
full work of the vacuum tube is
Sgiven attention as applied to the
.EChree subjects, namely: Radio tele-
graphy; Its uses at the Front; and
in general, the great service it has
rendered to America and her
Allies.
Whether they are simply trans
mitters such as those used at the
beginning of the War or whether
combined transmitters and re-
ceivers, the various vacuum tube
let's considerably outshine the older
spark sets and present many adj
vantages possible only with IN
dampt wave propagation. The
first and most important great ad-
vantage of course it the extreme
receiver when tuned to 1000 me-
tiers does not respond to a $50 me-
ter wave as was formerly the case
in spark work, thereby causing
serious Inference on other waves.
In the present instance it is even
possible to install a great number
of sets and operate them stimuli
taneouSly in the same district or
sector without interfering with
each other during transmission or
reception.
The second advantage, which is
also an important one, is that for
the same weight and the same
distance covered, undampt wave of
the kind mentioned here are
operated on approximately ten
times less energy than a spark set.
1t is at once evedent that the i'm
mediate result of this is of ire
mendous Importance, particularly
during war time. Another factor
is that vacuum tube sets are much
more portable than others CORES
ponding to the same amount of
power.
A third advantage, though a less
important one than would seem, is
that the undampt wave set is suit
able for radio telephony as well as
telegraphy without having to
modify it's construction in any way.
Radio telephony, of which we will
speak at greater length later on,
has not reached the same state of
practicability as the radio tele-
graphy on account of undesirable
operating conditions
Light in weight, robust, easy to
set in operation, permitting extern
sive communications with very
little interference, decidedly port
able, the vacuum tube unit our en-
emies did not possess was decidedly
an advantage in field work.
A set which was used most ex-
tensively during the War is the one
which we have named the "Army
Corps Type" Incidentally it was
the last one to be manufactured
in large numbers. The makeup of
this unit includes an oscillator of
two or three bulbs. The hetero-
dyne which serves for reception is
embodied in the transformitter it
self, where a single lamp is used
in the receiving position, without
antenna and ground. To this
vacuum tube oscillating system is
joined an ordinary receiver with a
telephone, and an audio frequency
amplifer indentical to the one
used in the TIPS, or ground sys-
tenn, where the first tube may serve
as deteetor, if it is not desired
to employ galina. Type CA. as it
is known among French radio men
is extremely remarkable in that
relatively great results are ac-
complished at the cost of an al
most negligible amount of energy.
The tubes consume a filament cur
rent of about II watts, while on the
. plate circuit is cosuned so milli-
amperes at $50 volts, in other
words, 20 watts, With 80 watts
total power consumption distances
of ESQ kilometers have been COW
cred employing an umbrella an
tenna supported by a No. 81 MILL
meter mast.
(Cl 1922 Science ard I,uentfon