The Washington herald., 1922-10-08
AUDION IS SECRET
OF RADIO CLARITY
AT LONG DISTANCE
Crystal DetectOr Is Good
For Only Is or 20
Miles.

No doubt you have read where
some big broadcasting station was
heard across the United States. You
probably have wondered how those
receiving could hear so clearly. 1t
wasn't because of their hearing.
The reason lies in their receiving
set with its amplifers.
A crystal detector is good for
about fifteen or wenty miles. Some
have done far better than this, but
this is the average. An audion de-
tector will bring in stations from
that up to 100 or even several hun
dred miles, depending upon its con-
nections. Now. to do better, re-
Quires amplification.
Each step of amplification in
creases the signal strength. Theo-
retically you can amplify without
limit, but practically there Is a
limit. and that is two or three stages.
Above that amount you amplify all
other noises. such as induction from
power lines. One experimenter
claims to have been able to hear
ny walk across the room
II 1t is desired to receive signals
from greater distance than your
detector will permit, it Is then neces-
sary to use an amplifier. IL yoa
find one step will not suffice. II Is
then necessary to put in a second
step Of application.
1t will be found that amplification
OF the second step over the first
step is many times greater than the
nrst step was over the detector.
1t is best to speak of a two-stage
amplifier with a radio chart below
1t. The wiring and fixtures of the
first and second step are alike. The
grid OF the second tube Is subject
to much greater voltage variations
than the grid of the first tube, pro-
ducing corresponding greater fuc-
tuations in the output circuit and a
greater respond is heard In the
telephones.
The extent to which the voltage
variation of the second grid may be
increased over that OF the first tuos
is represented in the drawing The
vertical lines represent the voltage
variations In the circuits they are
pointing to. The detector will be
taken as one. The transformer has
radio of three to one and magni-
hes the voltage from the detector
three times. which voltage produces
a fivefold variation in the plate cir
cult of the first amplifying tube
The second transforn=- :aagni-
fies this variation three times. max
ng the voltage variation on tn.
grid of the second tube forty-five
times the initial voltage. The volt
age impressed on the second grid Is
amplified five times in PASSING
through the second tube, giving the
effect in the plate circuit (where
your telephones are now 225 times
that of the detector.
That is not the actual occurrence,
but II is in this proportion. Some
transformers have different ratios,
one make being as high as ten 70
one. A third stage Of amplifica-
ton can be added in a similar
manner with remarkable amplifica-
tion, but three-stage amplifer re-
quires delicate adjustments and is
not recommended for any but an
experienced operator.
Inc ampilncatlon in a three-step
is so great that static is picked up
from all over the country. When
you amplify signals you also am
plify static. The ideal way Is to
increase you amplification Juss
enough to read the desired signals
II the tubes are not burned bright
enough they will not amplify to
such an extent. so you could stili
use your three steps if you had
them and not pick up distant sta
tions when atmospheric stations
were not so good.