Alexandria gazette. [volume] (Alexandria, D.C.) 1834-1974, 1922-08-08
RADIO NEWS
THE DEVELOPMENT OF RADIO
TELEPHONY

lELEEhO-N ..
While the introduction OF raalo
broadcasting of music and entertain
nent during the past year has orought
the radio telephone suddenly before
the general public, radio telephony
has brought the radio telephone sud
denly before the general public, RADIO
telephony has been q more or less re-
liable form of communication Tor de-
cade Ii is true that the early types
of apparatus like the early forms OF
all apparatus were crude and lnoper-
alive when most wanted and tunc-
toned without the all-eSsentlal vac
Uum tube.
The early forms of radio telephone
transmitters made use of osclliatlng
arcs as the source of radio frequency
currents. A carbon micr 1phone was
connected in the antenna circuit Tor
modulating the antenna current by
voice. The carbon microphone proved
TO be one OF the main drawbacks to
this form Of equipment since it caked
badly when other than very small pow
er was employed. The arc also, was
not dependable in its operation and
produced many undesirable sounds IN
the receiving set. II was used with
considerable success at times how
ever, as the writer can recall having
heard monograph. 6electiOns from
the opera Aida" from & radiOphone
station in New York City several years
was radio-telephone station in San
Francisco.
The radio frequency alternatOr was
also employed as source of sus-
tanned waves for radiotelephony with
considerable success on the wave
lengths around 5000 meters. Shorter
wave lengths than this could not be
obtained as the generator speed which
determines the frequency in SUCH a
device, could not be increased.
The development of the vacuum tube
with three electrodes and the use Of
this tube as an oscillator or generator
of radio frequency oscillations has
greatly Simplifed the problem of ra-
dio-telephony. The vacuum tube is
stable generator and viii oscillate on
very short wave lengths. that is. at
very high frequencies. This feature
makes radio telephone possible for
the amateur who is required by law
to conduct all his activities on 200
meters.
The use Of vacuum tubes as ampll-
tiers for increasing the small currents
which pass through the microDhone
transmitter allows the output of high
powered tube transmitterS to be sat
prior to the War. and in 1913 there
isfactorily modulated, a thing which
has never before been possible. with
the other types of radiotelephone
transmitters. The oScillatOr tubes
themselves are constructed in a num-
Der of different sizes to fit the needs
of various kinds of services.
At the present time there are about
$50 broadcaSting stations throughout
the United States. while the number
of listeners can only be guessed Ex-
periments are being conducted with
radiophones on ships at sea, so that
the radiOphOne service may be con-
Quoted independently of the regular
ships radio telegraph services
Tests were recently made with q
small tranSmitter mounted in an au-
tOmobile which showed that radiotele-
phone communication between and au-
tomobile moving at high speed and
fixed point can be maintained over a
distance of several miles.
With the modern tendency toward
the development of devices to save
time and labor there is little doubt
but that the impetus recently given
to radio communication is only the
beginning of the opening of new era in
communication