The Snowflake herald., 1922-11-24
BODY CAPACITY Is
CAUSE OF ANNOYANCE
Methods by Which Its Effects
May Be Avoided - Possible
Reasons for Fading Signals.

and if the operator touches his set
while listening to a concert, the sig
nails will fade out
This may be caused by body ca
pacity, and while some stations run
into it quite frequently, others are not
bothered at all. Those living close to
brOadcasting station will never be
bothered with it as it only occurs with
q very close tuning 1t is explained
by the fact that the capacity of the
body coming in contact with the set,
which is very finely tuned, is thrown
out of adjustment by the outside in
ductance.
There are several ways to guard
against it, and one of the best is to
line the inside of the panel with tin
foil or aluminium foil and ground it.
In pasting the tin foil on the back
OF the panel, it is cut away from all
binding posts, switch points or rods to
prevent short circuiting the set. There
is one exception to this, and that is the
ground binding post. If the tin foil is
pasted Sve- this, it is, of course, auto
matically grounded
Shellac will do to make the foil ad-
here to the panel, which will not have
to be dismantled to be lined, as the
foil can be placed on in small strips.
Another method of remedying the
effects of body capacity is by using
metal dials on the variocoupler and
variometers and in sets where the
variometers are very close to one an
other, moving them away will help.
Or in case it is not desired to change
the set, placing a nOnmagnetic ma
terial between the variometers which
are close to each other and grounding
it will remedy the i'll effects For this
case, a piece of glass such as photog-
raphers use, covered with tinfoil on
one side, is effective.
Fading signals have long been EN-
countered by amateurs when receiving
long-distance stations. In this case,
the signals from a goodly distance
away may be coming in loud and
clear and then without warning fade
away. In a few seconds they may
return with all their force, and then
himself, again the voices or music die
out Or fading may take the form
of varying intensity of signals, one
minute the operator being forced to
strain his ears to catch the sound
while the next voices may be loud
and clear.
There have been many theories adj
vanced for this phenomenon, and we
are giving today two of the latest.
The radio division of the Department
of Commerce is reported to be under
the impression that fading occurs
when a cloud passes between the.
transmitting station and the receiving
set. This theory has been one of the
most popular among the experts, and
recent tests have been made to obtain
more complete data. If the passing
cloud theory is good explanation
of fading there will be some new
radio development very shortly. The
effects of various types of clouds upon
the signals is being studied, and the
results of this study will be OF inter-
est to everyone interested In radio.
Government officials are interested in
eliminating fading, or overcoming 1t
as much as possible, largely from the
standpoint of the amateur, as the COM
mercial stations, having much greater
power than amateur sets, are able to
overcome the atmospheric effects to a
great extent.
; The other theory, which has a close
relation to the cloud theory, is that
fading occurs when the signals pass
through an area where rain is falling.
In this theory, the idea is brought out
in different manner. 1t is stated
in effect that clouds are a benefit to
the signals, but that the rain will
hurt them. The theory is that the
condensation of the particles of mois-
ture in the air which form the clouds
has the property of making this me-
dunn highly conductive to radio Sig
nails. Just before storm when there
is more condensation in the clouds, the
signals should be at their strongest.
When the storm breaks, and the air
becomes saturated, the condition is
said to change and the falling rain
actually grounds the signals. This
sudden. change in atmosphere is stated
as the reason for the varying intensity
In the signals.
An approximate method of measur-
Ing the antenna resistance is by means
of a condenser and calibrated 70
ohm resistance unit connected in Sc
lies. This so-called phantom antenna
is then connected with the antenna
and ground circuit to double pole,
double throw switch, so that the output
of the transmitting set can be con-
nected either to the antenna and
ground or to the phantom antenna cir
cult.
To find the antenna resistance at
onv wave length first tune the set TO