Evening star., 1925-09-12
FIFTEEN MINUTES OF
RADIO EACH DAY
BY JOSEPH CALCATERRA.
All Rights Reserved. Repro. Prohibited.
Get Into the Set-BuiIding Contests
Part Ill

! The time will soon be ripe for radio
shows in the leading Industrial CEN
ters OF the country. Practically every
community of any Importance will
have at least one of these shows and
| many of the larger centers will have
more than one.
In practically all cases, one Of the
| main features Of the program of such
shows is a set-building contest and
exhibition, with handsome prizes TO
those who use their knowledge of
radio and their mechanical skill to
build sets which are new, novel and
| ingenious
Most fans when asked why they
have not entered answer that they do
not feel that they are capable of com
peting with others who may have had
| a greater amount of experience in set
building. Others seem to feel that
! only builders of complicated and
elaborate sets of the super -heterodyne
type have any chance Of winning the
prizes and do not enter because they
do not have the necessary amount OF
money and time TO spend on the con-
struction of such receivers
While elaborate sets give the CON
structor an advantage in that they
enable him to incorporate a great
many novel ideas and arrangements.
you must also remember that they
also make 1t possible for many errors
to enter into the work and spoil his
chances OF getting a prize. Do not be
discouraged, therefore, if you cannot
spend lot of time and money in
Dullulns a set, because you stand as
much chance of winning prize with
a small set which shows signs of real
intensive thought as you do with an
| elaborate 10.tube set
In many cases sets are Judged in
dinerent assiffica tions, according TO
the number of tubes used in the set
In practically every ca Sc the age and
experience of the constructor is taken
into consideration.
There are really three main counts
on which the merit Of a set can be
judged. The first and, without a
doubt. the most important factor
which should be considered is that
of efficiency. To get a set bv the
| preliminaries. the set itself must have
been constructed along lines thai
make for efficiency. You must re-
member that a radio set is primarily
intended to receive radio programs eff
nciently, and that to do so it must
be constructed according to sound
electrical principles.
Important Characteristics.
In judging set | would allot 40
points TO efficiency. The efficiency
of set does not necessarily mean
| the ability to get long distance recep-
| ton. While distance reception is one
! of the factors which determine set
efficiency, there are other desira bic
! characteristics which are just as i'm
portant and which must not be sac.
rificed merely TO gain long -dista nee
reception.
| The next characteristic which de.
| termines the efficiency OF a set is Sc.
! lectivity. Regardless Of the sensi.
| tivity of set in picking up long dis
| tance stations. the set is of very
| little use unless IL combines with
sensitivity a good quality of selectiv-
| ity. to enable the set to tune asily
! from station 10 station without any
| disa greeable background of unwa nted
stations.
The next important characteristic
| of efficiency is tone quality. No radio
set is worthy of the name of a mn
sical instrument unless il delivers real
tone quality. Last but not Ieas-. the
set must be comparatively simple 10
tune. The number of tuning con-
trolls must be reduced to the mini
mum, so as TO facilitate the effort
necessary in tuning in stations. Each
of these points-sensitiyity for dis
tance reception, selectivity, tone quail
ity and ease OF control-are worth
10 of the 40 allotted to efficiency.
Taking out 40 points for efficiency
leaves so points for other desirable
| characteristics of radio receivers.
These other desira BILE characteristics
will he discussed in tomorrow's
article