The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1925-06-19

heterodyned note might escape But
in fact the naturalization is practical
in that no radiation need be expected
that will annoy neighbors. With the
set oscillating, an experiment was
made with receiver hooked up to an
aerial six feet away from the an
tenna used for the oscilating set.
Squeals could be heard from the os-
cillating receiver by the person tun-
ing it, but the family living on the
! floor below, using the other receiver,
| heard no squeal. And that is the OBJ
| ject of naturalization in the present
case
Naturalization Is effected by con-
Meeting a neutralizing condenser from
| the grid of the RF tube to tap on
the secondary of the 3-circuit coupler.
If commercial coils are to be used in
this set, any 3-circuit tuning coil may
| be employed. The usual type has an
inductance requiring .0005 mid.
variable condenser. Both coils should
be tuned by condensers of the same
capacity, for logging simplicity.
As commercial 3-clrcuit couplers do
not usually have tap for the neu-
tralfzation connection, this tap may
be made by the constructor. Slightly
raise the eighth turn from the grid
end of the secondary, scrape off a
little insulation, aad solder a flexible
lead thereto. The other end of this
lead goes to one side of the neutral
izing condenser, which of course is a
variable instrument.
Making the Coils.
If the coils are to be made at home,
Ii would consist of ten turns of No.
% single cOtton-covered wire on a
3-inch diameter tubing, and Ii would
be 45 turns of the same kind of wire,
wound in the same direction. The
coupling may be close, preferably
should be, as the added apparent re-
sistance makes for better stability.
The usual II Inch separation may be
used between primary and secondary,
if the constructors preference runs
that way.
The 3-circuit tuner would be made
of the same kind of wire on the same
diameter tubing, all windings in the
same direction. L3 would be ten
turns. If the coupling is close be-
tween L3 and LA and between ticker
and secondary, then about two extra
turns should be put on the secondary,
making At turns, as against the 40
for the RIFT secondary. The reason is
that there is an absorption effect,
which deprives the secondary ofsome
Of its inductive value. The extreme
ly loose coupling that would be re-
CURED If the secondary's value in
Invertebrates was to be what the In
ductance tables call for with a given
number of turns, is hard to realize
in practice. The ticker L5 consists
Of "a turns of No. % SSC wire on a
"a Inch tubing 21a inches high.
Each of the stator tubings is
inches high. The two coils, when
mounted, may be at right angles,
which is more easily accomplished by
having the RIFT mounted on the base
| board, it's axis parallel thereto.
The condensers for the coils as de-
scribed are 0005 MID. Straight-line
| frequency condensers will make tun-
| ing easier ON the low waves, as will
straight-line wave-length condensers.
These are distinguished from the
straight-line capacity condensers by
the fact tie preferred ones have
shaped plates.
List of Parts Needed.
One radio-frequency transformer
Gil, L2).
One 3-circuit coupler U3, Ia, L5.).
Two 15-Ohm rheOstats (R1, R2).
One 6-ohm rheostat (R3).
One double-circuit jack (J1).
One single-circuit jack (J2).
Two push-pull battery switches Isl,
so.
One .OOO25 mid. fixed grid con-
denser.
One variable grid leak (R5).
Two 00O5 mid. variable condensers
(C1, Coy.
One neutralizing condenser (N).
One 41a-volt G battery, or two Of
them.
Two 45-volt B batteries.
One storage A battery, 6 volts, 100
to 120 amp.-hr.
One by 24-inch panel.
One Z by 23-inch Dashboard.
Three 4-inch dials
Sixty-five feet of aerial, ground
clamp, lightning arrester, earphones.
speaker, connecting wire, screws, No.
IA insulated lead-in wire.