Evening star. [volume] (Washington, D.C.) 1854-1972, 1927-08-07
RECEIVERS REDUCE
RAD|OPHONE COSTS
Vacuum Tube System Brings
Cut in Huge Expense
of Transmitting.

Although the practicability Of ex-
changing transatlantic radiophone
messages was established early In
1928, it soon became evident that to
insure continuous and reliable commu-
nication both ways in all seasons tre-
mendous transmitting power would be
required at each end of the circuit.
In 1923 a powerful 200-kilowatt special
transmitter at Rocky Point, Long Is
land, worth nearly million dollars and
approaching the economic limit, was
used. The cost of the receiving set
used in England was insignificant In
comparison, and 1t was not much more
elaborate than an ordinary first-class
broadcast set. Needed improvement.
Ralph Bown of the American Tele.
phone & Telegraph Co. points out In
explaining the system, could most
economically be made on the receiving
end.
The new receiving station located
at Houlton, Me-, some 500 miles dis
tant from the radiophone transmitter,
is the result of four years work on
this problem. BY means of the
vacuum tube simplifying systems used
today 1t is no longer necessary to
operate tremendously high power
transmitters. for the sensitivity of
modern receivers makes audible even
the weakest signals. 1t was this tube,
according to Mr.. Bown, which upset
the economic balance between trans.
mitters and receivers used in long
distance circuits some years ago.
Since then large receiving antennas
have disappeared and receiving equip
ment has become cheaper, but, on the
al ~f III rvH, Sn~I
transmitting plants became prohibit
tive. Fortunately the receiving end
seemed to win out by gaining am
plifying power and high power was
no longer necessary.
Static Battle Won.
A long battle with static also was
partially overcome through the use
of directional antennas for receiving
stations. which actually reduced this
sort of interference to one five
thousandth, or increased the In.
coming signal to 5000 times what
it was originally at Riverhead, Long
Island. At Houlton, Me-, what
is termed a wave antenna," de-
veloped by the Radio Corpora
ton engineers. is now used. 1t re-
ceives only signals from a relatively
small angle, practically disregarding
those from other directions and static.
The particular antenna used at the
Houlton station comprises a system
of three three-mile antennas pointed
directly to the transmitter in England.
The result of improved reception Is
much tho same as If the power Of
the British transmitter had been in.
creased a hundred times.
Another special study convinced the
radiophone engineers that a receiving
site removed from the transmitter
would improve conditions materially,
and after a survey, Houlton was Sc.
lected as the most ideal location.
Static was less there than in the vi
entity of New York, where most of
It came from the southwest, whereas
incoming transatlantic signals ap.
preached from the northeast. I'm
provement in reception at the Houlton
site, therefore, Is now said to be ap.
proXimately equal to an increase in
transmitting power of SO times. Taken
collectively. the location and antenna
improvements meant an increase in
incoming signal strength of 5000
times, or 100 times for the directional
antenna and so for the location.
Huge Saving Claimed.
Since the transmitting plant in
England is rated at 200 kilowatts it
Is calculated that the improvements
at Houlton in reception are a tire.
mendous saving in power and there
fore money. To have secured as
strong and reliable signals in this
country, without changes in the re-
ceiving station, the England trans.
mitter would have had to have been
increased by 5000 times or to 1000, 900
kilowatts, a power transmitter
scarcely dreamed Of and of doubtful
practicability.
Many other improvements were
developed during the four years since
the first transatlantic telephony, and
incorporated in the present system.
The British Post Office engineers have
also worked on the two main prin.
ciples involved; that Is, site and direc-
tional antennaS. The effectiveness of
every kilowatt radiated from the
United States transmitter at Rocky
Point, is now being multiplied hun.
dreds Of times at their new receiving
station at Cupar. in northern Scot
land, where modern antenna systems
are used.
Advantages Recognized.
At the outset, the advantages of
long wave or low frequency trans.
mission were recognized. Today the
band used in transatlantic telephony
is only three kilocycles wide, but In it
there is the American transmitting
pchannel of 81 kilocycles and the Brit.
ish Of So kilocycles, indicating that
far less separation between channels
Is needed than in the better known
broadcast band. where 10 kilocycles il
necessary. To be sure, these two
channels are not used at the same
time. When no one is speaking the
two transmitting. paths are blocked
but the receiving circuits are open.
When an American speaks in New
York, for instance. the apparatus au.
toma tically closes his receiving circuit
and opens the one for transmission to
the London circuit, which is set for
reception.
When the American finishes, his
apparatus Immediately closes for
transmission and opens for reception,
SO the London speakers voice is
heard. Interlocking arrangements
prevent both speaking at the same
time, permitting only the first wire to
carry through the circuit. AS far as
the subscriber knows, the radio cir
cult functions much as in an ordinary
line conversation between two cities.
except for some radio noises unhea I'd