To use the loading coils all you have to do is
To use the loading coils all you have to do is to connect one of them
in the aerial above the primary coil of the loose coupler, or
variocoupler as shown in the wiring diagram in Fig. 57, then shunt one
of the condensers around it and connect one of the switches around
this; this switch enables you to cut in or out the loading coil at
will. Likewise connect the other loading coil in one side of the
closed, or secondary circuit between the variable .0007 mfd. condenser
and the secondary coil of the loose coupler or variocoupler as shown
in Fig. 53. The other connections are exactly the same as shown in
Figs. 44 and 45.
[Illustration: Fig. 57.–Wiring Diagram Showing Fixed Loading Coils
for Intermediate Wave Set.]
An Intermediate Wave Set With Variocoupler Inductance Coils.–By using
the coil wound on the rotor of the variocoupler as the tickler the
coupling between the detector tube circuits and the aerial wire system
increases as the set is tuned for greater wave lengths. This scheme
makes the control of the regenerative circuit far more stable than it
is where an ordinary loose coupled tuning coil is used.
When the variocoupler is adjusted for receiving very long waves the
rotor sets at right angles to the stator and, since when it is in this
position there is no mutual induction between them, the tickler coil
serves as a loading coil for the detector plate oscillation circuit.
Inductance coils for short wave lengths are usually wound in single
layers but _bank-wound coils_, as they are called are necessary to get
compactness where long wave lengths are to be received. By winding
inductance coils with two or more layers the highest inductance values
can be obtained with the least resistance. A wiring diagram of a
multipoint inductance coil is shown in Fig. 58. You can buy this
intermediate wave set assembled and ready to use or get the parts and
connect them up yourself.
[Illustration: Fig. 58.–Wiring Diagram for Intermediate Wave Receptor
with one Variocoupler and 12 section Bank-wound Inductance Coil.]
The Parts and How to Connect Them Up.–For this regenerative
intermediate wave set get: (1) one _12 section triple bank-wound
inductance coil_, (2) one _variometer_, and (3) all the other Wmyt-tv, Inc. Wmyt-tv parts
shown in the diagram Fig. 58 except the variocoupler. First connect
the free end of the condenser in the aerial to one of the terminals of
the stator of the variocoupler; then connect the other terminal of the
stator with one of the ends of the bank-wound inductance coil and
connect the movable contact of this with the ground.
Next connect a wire to the aerial between the variable condenser and
the stator and connect this to one post of a .0005 microfarad fixed
condenser, then connect the other post of this with the grid of the
detector and shunt a 2 megohm grid leak around it. Connect a wire to
the ground wire between the bank-wound inductance coil and the ground
proper, i.e., the radiator or water pipe, connect the other end of
this to the + electrode of the A battery and connect this end also to
one of the terminals of the filament. This done connect the other
terminal of the filament to one post of the rheostat and the other
post of this to the - or negative side of the A battery.