Evening star., 1925-01-25
WAVE LENGTH TESTS.
BY HOOVER LAUDED.
Seeming Mystery to Fans
Merely Painstaking Effort to
Improve BroadCaSting.
BY CANL IL. TNIAN.

wave lengths in the DAD asst ned
seems to be q mystery TO many fans
despite considerable comment in the
press each day. Briefly. he is trying
to improve condition in the broad
casting traffic. and has put every
available channel in use.
When the third national radio CON
ference met in Washington last Oc-
tnter e. plan for the reallocation OF
wave lengths in the whole field of
radio transmission was proposed
chiefly in an effort to reduce inter
ference and to create more channel
for the growing broadca sting serV-
ice. At that time there were 5l9
roadcastin2 stations OF three classes.
They included 81 class 3, or higher
powered station ; IS class 4 and SS2
class stations, the last stations on
the original broadcast wave of $50
meters. Many more stationS were
contemplating transferring to class 4
status, but wave lengths were getting
very scarce in that group, where each
station desired and expected an in
dividual and eNclu i've air route
Past Years Developments.
Developments in the past year had
shown that many stations were
reaching 4 position in type OF pro-
grams. territory covered and rtli-
zbility OF equipment which made it
desirable to grant them exclu-
sive wave lengths and more power
in the interests of hieh-class pro-
grams and public service. This was
done gradually, and 81 stations
were on the air when the conference
met, besides which about 20 more had
applied or were preparing 10 ask for
class b status. After considerable
deliberation the conference laid out
plan for ALLEGATION which would
provide ~ separate channels for dis
tributton among the class B stations
come few of which il was realized
would have to use the same wave
length Distance and time, it was
believed, would make this practical.
But the class 3 applications began to
increase. and when the field repre-
sentatives OF the department tried to
argue with the owners of high pow
er"d stations to split time and shift
their channels difficulties increased
materially. The original conference
plan had to bs abandoned. 1t proved
impractical. although il was interest
ing on paper
During the past three months the
radio experts of the Department of
Commerce have tried out several
other plans for increasing the num-
Der OF channels in the band allotted
70 the r stations. but to date they
have arrived at no practical scheme
which insures satisfactory arrange
ment between the broadcasters and
the fans
They have eliminated the old class
stations, which have carried on on
the 500 meter wave. or practically so !:
only about a dozen remain The
others have either transferred to
classes A or B or dropped out OF the
serial entertainment game. No more
class c stations are being licensed
This leaves only two classes of broad
casters, except for two stations carry
Ing on experiments under what is
termed class d or development licenses
To qualify as class station spe-
cal requirements are necessary. Stu
dio arrangements TO eliminate reyer-
oerationS must be made: equipment
must be such as to prevent harmon
tcs; special antenna must be erect
sd so as TO prevent swinging, and re
liable equipment, with spare parts.
must be used. These stations are
granted power between 500 and 1000
watts, and in a few cases as high as
$500 or 2,00o watts. They operate on
wave lengths between 2s0 meters and
a45 meters. High class proSrams are
required, which precludes the trans
mission OF mecha nical music such as
phonograph records
Glass A stations are those operat-
fnE with 500 watts power or less
They are assigned channels between
zno and 21S meters. There are $50 OF
these stations on the air. Supervisors
of radio have pretty well settled the
wave ALLEGATIONS OF all these stations
lp their districts, but the wave lengths
are practically all repeated in each
OF the nine districts, except along the
horderlands between them
Departments Real Problem.
The real problem before the Depart
IN NnI of Com .
nting the class wave lengths with
out making the interference worse
than it is today. On January II there
were 70 of these stations in opera
tion and 20 more contemplated. In
other words, there are approximately
~ wave channels, 10 kilocycles apart.
Tor the use Of 80 stations Obviously
each station cannot have separate
wave length
Some changes have been made tenn
porarily, but no definite list of per-
manent wave lengths has been an
nounced
All stations which have been shifted
curing the tests have been published
IN these columns, and the wave
lengths OF all new Glass B stations
have been announced.
mere are only three methods which
the chlef supervisor of radio ca n fol-
low in his effort to untangIe the ma
uohAl proa dcsstIng situa tion: He can
squeeze the stations closer together.
that is, decrease the separation from
~ kllocycles, on graduated scale
down to about : klocycles; he
can make all stations divide time on the
same wave length, or he can dupli-
can't wave lengths in a sort Of coming
system across the country The cues
ton is which is the best of these
schemes. Increased power for seven
Z Gf
further complications, as these sta
tions, although divided by the breadth
of the continent, now begin to inter-
fere, whereas they did not do so with
SEQ watts.
During the recent tests with wave
lengths closer together. in an effort
to create additional channels MANY
protests that the stations operatinar
on adjacent channels could nor he
separated, were received. Except with
very selectiVe receivers difficulty in
separating stations only I kiIo-
cycles apart was found. The fans OBJ
jected TO fine tuning
On the other hand, this is the only
known method creating more chan
nehs If the second scheme requiring
stations to divide time on given wave
lengths, was followed only about half
the stations could operate at once.
and If wave channels were duolf-
Gated there would be interference on
practically every wave length all the
time, as at least two stations would
be using the same channel simulta-
neously
Considering these plans. it would
appear that the first method is sener-
ally the best, but the problem of ed
ucstfng the fans to this belief re-
mains TO be accomplished before peace
in the air is secured