Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-02-16
Behind the Microphone
BY THE RADIO EDITOR.

there are no inventions which will
alter the design of the modern
receiver this year. That excep-
ton is the recently announced
fiVe-element pentode tube. This
tube, which has both shielded grid
and shielded plate, is virtually
screen grid tube now in use. It's
difference lies in the addition of
a terminal on the side of the base
for the new element. It also func-
tionS similarly to the conventional
screen grid tube, its main advan-
tage being that it affords addi-
tional gain in amplification. The
tube, however, is too new to de-
termine whether manufacturers
of receiving sets will incorporate
it into their latest models this
year.
Aside from the pentode tube,
there are no new engineering de-
velopments in view. A statement
recently issued by Walter E. Hol-
land, director of the engineering
division of the Radio Manufacture
ers' Association, declares that
purchasers of standard radio re-
ceiving sets have every assurance
that they will not be obsolete by
new developments"
The years outstanding develop
mentS, therefore, will be confined,
most likely, to the cabinet and
mechanical design.
II X 4
CONSIDERABLE progress has
been made in recent weeks by
the Radio Manufacturers AsSoci-
alton in the Standardization of
radio nomenclature and appara-
tus. Definitions for a number of
commonly used terms in connec-
ton with receiving sets have been
drawn up. Most important among
these are the following:
Screen grid receiver"-A re-
ceiver in which all the radio-fre-
quency amplifier tubes are screen
grid tubes, employed as such.
~ inform Selectivity" - The
characteristic of a receiver by
which it is equally capable of dis
eliminating between signals of
the same intensity at any point in
the broadcast frequency range.
~ inform senSitivity"-The
characteristic of a receiver by
which it is equally capable of re-
spending to broadcast signals of
the same intensity at any point in
the broadcast frequency range.
Automatic volume control
means whereby a receiver accom-
modates itself to the strength of
the received signal within limits
depending on the characterize
ton of the signal, but without af-
fecting the quality preadjusted.
Linear detection"-Any form
of rectification in which the au-
dio-frequency output voltage is
substantially proportional to the
radio frequency input voltage
throughout the useful range OF
the device.
7. e. SMITH, president of the
National Radio Institute, has
just compiled some interesting
} statistics showing that more thar
1000 patent applications covering
radio developments are now pend
ing before the Patent Office.
Smith said this rather startling
revelation recalled the story OF
the wise and far-Sighted young
man who resigned his position in
the Patent Office many years age
with the announcement that "ev-
erything worth while had beer
invented"
The airplane, monograph, ray.
on, talking movies and radio
were never dreamed of at tha'
!. time. Yet inventions are comine
in for patent at the rate of $4,000
year. AS for radio, the great
number Of applications pendine
Is an indication of the tremen-
dous development going on ir
this comparatively new science.