The Washington times., 1925-01-26
COOLIDGE TALK IN AIR TONIGHT
Romping Around
Radio Dial


suits Of the new change in wave
lengths has been submitted to us by
A. l.. Groes, "3 BID" of Brooke, Va.
I'm the first place." Mr.. Groves
writes, 1.-The ear is responsive to
variations below 10000 cycles per
second, and the first radio confer
ence very wisely recommended that
radio stations be spaced 10000
cycles 40 kilocyeles) apart to avoid
audible beat notes (heterodyning) be-
tween them. Even with this separa
ton which is on the very border
line, many stations find it most diff
cult to keep the wave constant
enough to prevent heterodyning.
Imagine, therefore, the situation
with all stations working only z or
s k. c. apart
LAS you rightly stated, at pres
ent the situation seems improved
in certain respects. However, re-
member that all of the stations
have not been crowded up on the
higher wave lengths yet and that
when the bunch gets going you
will hear nothing satisfactory, only
squeals due to the heterodyne
effect that is bound to occur when
two stations are transmitting less
Cannot Stop Interference.
There is no receiving set that
can get around this type of inter-
ference-the trouble can not be
remedied at the receiving end, but
any fairly selective receiver can
select one station from another
and experience no cross talk inter
ference and no beat notes or choked
atRA ste 1s H.
mitters are 10 H. c. distant.
This does not apply to tuning
out distant stations of course, but
the point Is that as long as the
stations are spaced 10 k. G. apart
the degree Of selectivity obtainable
depends upon the receiving set
II also agree with you that the
short waves are "a ness at
present, but this. is due mostly to
the transmitters being off their
assigned frequency However
there is a band that is exceptional
WILD, KDKA, KGO, WGBS,
WGR, KOA, WSAI and WBZ
These stations almost never vary
in their frequency, no beat notes
occur and any one of them can be
selected easily without interference
from the other. However, when
WMBF, at Miami, comes on he
heterodynes WBZ."
In the lower wave bands Mr..
Groves states that he finds many
OF the stations off their frequency,
namely WNAC, WREO, xxx,
WEAO, WPG and WTAS.
"Of all OF these" he states, "only
enough to their assigned freQuen.
cies to prevent heterodyning an
other"
One Solution Suggested.
As solution ror the problem,
MIR. Groves suggests that "ali class
B stations be assigned 10 k. C. apart
on waves between 200 and 357
| meters. This will give sixty-five
channels for this service which is
several more than can be gained
/ by packing them Z k. c. apart on
the long waves.
Then if any z X. G. separat ton
is necessary, assign class A stations
all waves from 361 to 545 meters at
Z k. c. apart which will give them
two or three more channels than
they have at present.
las the class a stations are
never local in character and less
powerful than class B stations the
, heterodyne effect would not be
nearly as severe nor extensive as
will be caused by class 3 stations
! under similar separation
! An interesting week of broadca st
programs is scheduled for the com,
ing six days with the Brunswick
Hour OF Music tomorrow night and
! the Victor concert on Thursday,
, The Brunswick Company has an
nounced that it's concerts in the
future will be begun at o'clock
eastern standard time instead of 10
o'clock as in the past. That's a
help.
/ WHAA, Iowa City, has changed
it's call letters to WSUT, which of
course is more appropriate to the
/ State University Of Iowa
Wave lengths changes include
! VIVID. Mooseheart, which is now
! 306; WEEP. Boston, which has
climbed above 400 metres some
where and WTAM, Cleveland, which
Saturday night was operating on
j 1851.