Evening star., 1925-08-28
FIFTEEN MINUTES OF
RADIO EACH DAY
BY JOSEPH CALCATERRA.
All Rights Reserved. Repro. Prohibited.
Pointers on Getting the Most From
Your SuperheterOdyne. Part III.

After you have found that your
tubes are all in good condition you
should try them in different positions
in the circuit. changing them around
until you find the positions in which
they will work to best advantage.
1t is especially important to get a
good first detector tube and good
ostcillator tube A little experiment
ing will also show which tubes are
best fitted to perform the function or
intermediate ampliflers.
When you have them placed in the
best positions mark or number the
tubes so that If you find 1t necessary
to take them out you Will be able to
replace them in the same position.
Test All Parts.
Grid leaks, grid condensers and by
pass condensers will also bear investi-
cation. II you have no means of
testing them play safe and get those
made by a reliable manufacturer who
has a reputation to maintain.
It is best to test out transformers
and other coil windings before they
are connected into the circuit. If,
however, you neglected to do this and
are experiencing trouble it will pay
you to disconnect the coil terminals
and test each winding carefully with
voltmeter and battery to make sure
that there are no open circuits in the
windings.
In some cases It Is not necessary
to disconnect the terminals but it is
best to play safe and disconnect them
altogether if you are not expert in
tracing circuits and deciding whether
it is or is not necessary 70 discon-
meet the wiring
Use Good Sockets.
Efficient tubes will not give good
results If they are used with poor
sockets. Sockets should be of the
best. Bakelite or hard rubber sockets
will give best results. Mud" compo-
sition sockets not only introduce
losses because of poor insulating
value of the composition but they
also have such poor heat-resisttng
properties that the application of a
soldering iron to the terminals softens
the material which holds the socket
springs in place and causes loose
connections.
Socket springs and terminal should
be frightened before the sockets are
connected into the circuit. The
terminals should also be tried after
they are soldered in place to make
sure that the heat of the soldering
operation has not loosened the ter
minals.
Some fans are puzzled by the fact
that a station can be tuned in on
different settings on the dials. This
is a property peculiar TO the super
heterodyne and is a result of the fact
that the beat frequency on which the
action of the circuit depends can be
produced by adjusting the oscillator
circuit to point either below or
above the incoming frequency.
Importance of Loop.
Remember that it is Just as i'm
portant to have a loop of the proper
characteristics as ii is to have a prop
erly tuned internal circuit When
ever possible use loop of the dimen-
sions and characteristics given by the
author or manufacturer. If you have
a different loop you can use it if you
make allowances for the difference in
characteristics. If your loop is
smaller in size, you will need more
turns than called for by the specifica-
tions; If 1t is larger then a smaller
number of turns will suffice. You
can either tap the loop or make the
connections on different portions until
you find the proper point on the turns
which gives the best results.
No set of instructions on the opera
ton Of set is complete without the
admonition to use the proper battery
voltages and to make sure at fire.
quent intervals that the batteries are
up to the mark.