The Washington herald. [volume] (Washington, D.C.) 1906-1939, 1922-04-07
Questions and Answers
Misprint in Answer.

Mfsprfnt In Answer.
H. S. BY an error in answer
to your question appearing in yes
terday's Herald you were told to
connect the antenna lead near the
loose end of coil, and antenna lead
midway of COLI: this was intended
to read: Connect detector lead
near loose end of coil and antenna
lead midway of coil"
OscilIatory Circuits.
o. What is meant by an oscilla-
tory current?
OBJ. What is an osciIlatory cir
cult? N. E. j.
A. (a) 4 current which flows
| first in one direction and then in
the other, changing its direction
many times per second. Radio cur
rents may make this direction
change millions of times per Sec
ond.
OBJ. A simple oscillatory circuit
consists of an inductance, capacity
and resistance. The current through
such a circuit would be of the
above frequencies.
Phones in Open Circuit.
Q. Why are telephones not con-
nected directly in the antenna cir
cult? L. F. NJ.
A. In modern sets using a Sec
ondary circuit the phones are not
in the antenna circuit because the
telephone diaphram is not made to
respond to currents of radio fire.
quency. What Is known as i'm
pedance in the phone coils-ob-
structs currents of radio frequency
and records only those below ap-
proximately 10000 cycles per sec
| ond frequency. They are connected
in the closed or secondary circuit.
Grid Wire.
Q. (a). What kind of wire is
used for the grid in the vacuum
tube?
OBJ. What is the real purpose of
the, gridi L. H. D.
A. (a)- Usually platinum. copper
or tungsten. Different metals are
also fused for grid wire.
OBJ. Theoretically the grid OBJ
structs the passage of electrons
radiated from the lighted filament
of the tube. or as stated by Arm
strong: The grid element when
placed in the path of the electrons
receives a negative charge which
decreases the current flowing be-
tween the plate and the filament,
(maintaind by the B battery.
Weak Signals.
Q. have an audion detector re-
ceiving set. / catch local music
very family. At times it will get
very close and loud. then become
faint again. Please tell me how
can overcome this? T. V.
A. Yur neiGhbors are undoubtedly
tuning. resulting in a detuning ef-
feet on your set. The only remedy
for this is to find the miscreants
and ask their forbearance. The fol-
lowing faults may be present in
your receiving set: A-battery get
ting weak, reducing flament cur
reEt; antenna disconnected or
grounded; B-battery low or grid
leak off. If the reception of distant
stations is bad very likely your
trouble is due to what is known as
fading, namely signals alternating
strong and weak. 1t has va -ious
causes, some of which are: Fluctua-
tions in the wavelength of the
transmitting station: wind blowing
your antenna or that of the trans
hitting station causing 1t to swing:
operator not talking directly into
transmitter lin case of radlophone
transmission. II your set is all
right the best you can do is to try
to keep tuned to the t "ansmitted
wave fluctuations by varying your
I~inductance and CAPACITY. IT rs like
game of tag to keep up with the
incoming wave trains. This condi-
ton is often encountered aboard
ship. particularly during storms,
when the operator continually
keeps one hand on the condenser
and inductance knobs to avoid
missing signals. The same condi-
ton exists when airplanes transmit
due to their constantly changing
attitude and distance from the re-
ceiving station. The effect is more
noticeable on short waves.
single Tube Receiver.
Q. A statemnt appeared in the
radio column some time ago that
one could not get Pittsburgh with
a single tube receiver. / have had
no trouble getting Pittsburgh, in
fact as loud as local stations, with
the exception of NOF V. A. NJ.
A. There was no intention of say
ing anything unfayorable about the
single tube receiving sets, nor can
their range be definitely stated.
Simple crystal detector sets have
received over longer distances than
from here to. Pittsburgh. But. the
fact remains that with a single tube
weak signals will not be detected,
no ampliflcation and very. limited
range of tuning Is possible. due t.
the absence of sufficient capacity
and inductance variations, With
little interference the single tube
sets are quite efficient.