The High Tension Condenser.—High tension
condensers, that is, condensers which will stand up
under high potentials, or electric pressures,
can be bought in units or sections. These condensers
are made up of thin brass plates insulated with a
special compound and pressed into a compact form.
The capacitance [Footnote: This is the
capacity of the condenser.] of one section is enough
for a transmitting set using a spark coil that gives
a 2 inch spark or less and two sections connected
together should be used for coils giving from 2 to
4 inch sparks. It is shown at e.
Connecting Up the Apparatus.—Your sending
set should be mounted on a table, or a bench, where
it need not be moved. Place the key in about
the middle of the table and down in front, and the
spark coil to the left and well to the back but so
that the vibrator end will be to the right, as this
will enable you to adjust it easily. Place the
battery back of the spark coil and the tuning coil
(oscillation transformer) to the right of the spark
coil and back of the key, all of which is shown in
the layout at A in Fig. 20.
[Illustration: (A) Fig. 20.—Top View
of Apparatus Layout for Sending Set No. 1.]
[Illustration: (B) Fig. 20.—Wiring
of Diagram for Sending Set No. 1.]
For the low voltage circuit, that is the battery
circuit, use No. 12 or 14 insulated
copper wire. Connect all of the dry cells together
in series, that is, connect the zinc of one
cell with the carbon of the next and so on until all
of them are connected up. Then connect the carbon
of the end cell with one of the posts of the key,
the zinc of the other end cell with one of the primary
posts of the spark coil and the other primary post
of the spark coil with the other post of the key,
when the primary circuit will be complete.
For the high tension circuits, that is, the
oscillation circuits, you may use either bare
or insulated copper wire but you must be careful that
they do not touch the table, each other, or any part
of the apparatus, except, of course, the posts they
are connected with. Connect one of the posts
of the secondary coil of the spark coil with one of
the posts of the spark gap, and the other post with
one of the posts of the condenser; then connect the
other post of the condenser with the lower spring
clip of the tuning coil and also connect this clip
with the ground. This done, connect the middle
spring clip with one of the posts of the spark gap,
and, finally, connect the top clip with the aerial
wire and your transmitting set is ready to be tuned.
A wiring diagram of the connections is shown at B.
As this set is tuned in the same way as Set No.
2 which follows, you are referred to the end of
this chapter.
