Evening star., 1924-11-15
FIFTEEN MINUTES OF
RADIO EACH DAY
BY JOSEPH CALCATERRA
Radio Editor of Popular Science
Monthly.

All Rights Reserved. Repro. Prohibited.

The Low-LoxS Wave Hit. Radio.
1t seems that just as soon as all in
austry or all idea gets going along III
the even tenor of its way something
IS bound to happen to upset all tradi-
tions, change ideas and play the mis-
chief with all accepted facts and
dosmas.
Radio WAS going along very nicely
with heavily shellacked coils. tuning
coils. tapped coils, condensers with
plenty of dielectric materials. paper
fixed condensers and generally inefficient
apparatus when somebody began think
ing in terms of microamperes. and be-
gan to figure out the losses that take
place when electron meets clcctron
without a proper and formal introduce
tion.
The result vas that radio began to
take forward strides in 7-leaguc boots.
Manufacturers began to vie with one
another in the design Of the lowest loss
apparatus, 50 that every iota Of pass
ing radio energy could be harnessed and
made to do its bit.
Electrons we're herded together as
they passed from one point Of circuit
to another; roads were paved and ma de
as reststancelees as possible: turns and
detours were eliminated or proper'y
charted and, in short, everything was
done to make the passing Of the re-
ceiVed energy through the various
mazes OF radio circuits as easy as it
was possible to make il, so that the re-
ceived energy arrived in full strength
at the reproducing mechanism, namely.
the phones or loudspeaker.
Attacks on ARtenna.
The first attacks were made on the
antenna system. The Importance Of US
ing a single continuous length Of wire
for antenna span and lead-in was
stressed; the value OF erecting a high
antenna clear OF surrounding objects
was emphasized the necessity of using
=. very good ground connection was de-
liberated upon, and the result was the
conservation OF considerable amount
OF energy which formerly went to waste
The next step was to improve the
tuning units and elements of the re-
ceiver. Tests were made on various
materials and methods of winding
fnductances and variocouplers, vario-
meters. spiderweb coils. honeycomb
coils, low-loss tuners using very low
resistance high frequency cable of
the Litz variety; aperiodic and semi
aperiodic windings to eliminate
taps, claTfyngi variable seiectors,
tuned radio frequency transformers
and various kinds OF specially wound
coils made their appearance, each
having it's own advantages.
Shellac and other such materials
for keeping windings in place were
placed on the index expurgatorius
list of taboo materials. Tests
brought to light the fact that a self
supporting coil Of the honeycomb
type made the best type Of induc-
tance where such coil could be
used while low-loss materials which
could be formed and nodded were
developed for use where such sup
porting structures were necessary.
Ineficient friction contact devices
gave place to long bearing surfaces
for such contacts or to pigtail con-
nections Taps soon became lost in
the shuttle and highly efficient tun-
ing devices which did not require the
use of such taps supplanted, the old
type Of tapped coils.
The same process OF refinement
was applied to variable condensers
the old methods OF construction gave
way to new designs which eliminat-