The Rock Island Argus and daily union. (Rock Island, Ill.) 1920-1923, 1922-03-18
PART ".
The Timer.

The tuner, or combination of in
struments used to tune the receiv-
ing set to the same wave-length as
that of the sending station, is the
first part of an audion set the aver
age amateur attempts to build,
probably for the reason that it is
a little easier than the audion con-
troll panel
The design or arrangement of
the instruments on the panel has
much to do with its working, as
when the wires connecting the in
struments are long, through poor
design, there is apt to be consid
cradle capacity" effect between
the wires, thus causing marked
reduction in signal strength and
sometimes noises in the set. In de-
signing tuner it is best to look
over the designs shown in the cata-
logues of reliable manufacturers.
OF course the first thing to be de-
cided upon will be the circuit to be
used, of which there are many hun
dreds. For all-around general re-
ception of all wave-lengths, the
three-coil ticker feed back, using
honeycomb coils, is the most eff
cient. One thing about this type of
tuner is that, while all wave-lengths
may be received by use of the
proper sized coils, only three coils
need be purchased at first. These
coils may be of any size, depending
of course on the wave-length it is
desired to receive. Generally coils
to receive amateur and broadcast
ing stations (these are the small
est coils are the first purchased.
A bakelite panel is the best thing
to mount the instruments on, and
great care is necessary, when US
ing other material for the panel, to
prevent any leakage of the very
feeble currents. A panel for a
three-coil tuner using a coil mount,
two variable condensers, and SER
les parallel switch, may be as small
as by 10 inches. A good size is
9 by II inches and either one
eighth or three-sixteenth inches
thick.
When the tuner and detector
panels are built separately, the let
generally seems to work better, as
when they are on the sam panel
there may be considerable capacity
between the instruments, as well
as the wiring.
The usual arrangement of the
instruments of such a tuner is as
follows: The coil mount is placed
in the center of the panel, about
2h inches down from the top; the
two condenserS are placed one on
each side of the panel, as close as
practical, and so the side of the
condenser is in about three-fourths
to one inch from the side of the
panel. If series parallel switch
is used, it is placed in the space
between the condensers at the bot
tom of the panel. Two binding
posts are usually mounted on the
left hand side and four on the right
hand side, the two on the left be-
ing to make connection with the
antenna and the ground, while the
two on the right are for the pur-
pose of making connection with the
audion control panel.
Wiring up the set is where the
majority of the amateurs fail. They
either do not make good connec-
tions, sometimes by twisting wires
together so there is no connection
at all, or try to colder a connection
and not making the solder stick,
leave it and say, We'll, that one
little connection will not make any
difference anyhow" The wiring is
about the most important Part and
should be done carefully. Wiring
diagrams are to be found in the
catalogues of nearly all manufac-
turers of radio apparatus. A good
size wire to use is No. IS rubber
covered fixture WIRE" obtainable
at any electrical shop. Wherever
possible the wires should lie fas-
tened under a washer frightened by
a nut or screw. When these are
not provided for on the instrument,
it is necessary to solder the con-
nection. When soldering, always
be sure the iron is timed" and
heat the pieces being seldered I'M
I'll they themselves will melt the