Evening star., 1923-11-25

ernment are rushing work to perfect
telephone radio sets for transmitting
from airplanes in flight. Such trans
mission is. of course, not new. but
efficient sets answering specific re-
auiremets are desired by the Army air
service. the Marine Corps and the
post office air mail service. The prob
lem cannot be worked out jointly,
since the specifications are not SINH
lar.
Ever since the armistice the Army
has been trying to develop combina-
tion radio telephone and telegraph
set suitable for airplane use, and mas
just about succeeded. Recent tests
with model set S. c. r. 1874, between
an airplane flown back and forth
from Boiling Field. Anacostia, ID. z.
to Quantico, Va. about ty-nve
miles. and the radio laboratory or the
Signal Corps in Washington, proved
the set was practically perfect. out
siders listening-in on the two-way
conversation were deeply interested
following the engineers conversation
carried on over NAA at Arlington,
and then picking UP Capt. Johnsons s
replies on 400 meters from the plane
The sample transmitter built by the
General Electric Company was round
to be satisfactory. the main object
being the motor alternator. which
furnishes the tone for the 1nterfupteo
c. w transmission, which, IT - felt,
can be readily corrected and produc-
tion orders placed.
Marine Corps radio and aviation ex-
perts recently tested out a new serV-
ice combination set for use in air
planes. but without very successful
results, due chiefly to bad weather
conditions requiring low flying. Con-
versatIon between officers in the Navy
building, however. and capt. P1erce
in a plane over Quantico was carried
on but further tests VIII be neceS-
sary What the marine flyers wani is
short-wave telephone set using
around 100 meters. whereas they have
been forced to use "a transmitting
wave of 500. which they. claim Is too
long and productive OF harmonics.
Navy set l345 is therefore being modi-
fled and improved. Other tests In
spotting practice held at Quantico,
wherein a plane gave phone reports
on target practice. proved satislac-
tory. The operator in the plane was
heard as far away as Baltimore py
radio fans who were listening in
For air-mail pilots. who ny alone
on their transcontinental trips. the
Post Office Department Is seeking
"one- man" radiophone set which can
be operated by the pilot while under
way Radio telegraphy is useless Tor
mail routes. in the opinion of postal
authorities since they haven't room
for AN operator and do not require
their pilots to learn code. fadio
telephony, therefore,. carries the
whole burden OF aiding in aerial
flight. getting orders. calling for AID
and directions. A special small and
compact telephone transmitting set
to operate on about 125 meters IS de-
sired. Tests have just been made on
a new set developed by the General
Ia ,.t.
10 ESQ meters. Speech is sent out
through five fifty-watt XII transmit
ting tubes. The receiver uses seven
UV 1873 tubes. The operation ana
fer from sending to receiving is made
by throwing a switch. After a years
work practical standard set has
been adopted and an appropriation
providing for a set for each plane
will be sought. The necessity OF
the difficult problems. but IL had 10
be solved in the interest OF carrying
as much mail as was possible.
Strangely enough, the Navy takes
an exactly opposite view on radio
airplane communication from the
postal authorities: naval flyers have
practically abandoned the telephone
set and use only radio telegraph. all
the pilots being skilled in code trans
mission.
ship stations interfere.
With the elimination of amateur
interference with broadcast pcep-
tion through the government reguia-
ton providing for evening quiet
hours" the Department Of Commerce
is now faced with a serious situation
that threatens the pleasure of many
thousands of listeners--namely. the
interference which is being caused
nightly by scores OF ship telegraph
stations.
1t was comparatively an easy mat
ter to obtain the cooperation of the
amateur through his organization, the
American Radio Relay League, but
the proposal to keep silent ship radio
stations that are handling life and
death messages is another matter
Ship transmission is vital to safety
at sea and to commerce.
One the one hand are thousands of
listeners clamoring for relief from
interference that is spelling their
concerts and on the other the posi-
lively essential ship and commercial
air traffic. Commercial stations. both
ship and shore, use that band be-
tween 900 and 5000 meters. The Navy
employs waves from 600 upward.
while the Army. which causes very
little interference. follows the Navy.
Among the national organizations
which have announced their inten-
ton of bringing this matter be-
fore the Department of Commerce Of
ficials is the National Association of
Broadcasters. the executive chairman
of which. Paul B. Klugh. says: we
agree that ship-to- shore and COM
mercial stations on radiophone wave
lengths. during popular broadcasting
hours are the real disturbance to un-
interrupted reception. We hope to
bring some regulation of this at
Washington.
The uninformed broadcast listen
ers. enraged by interference. feel
that they mus blame some one
and the amateur seems to be the in
cvitable target. This condition can
be much relieved