The Birmingham age-herald. [volume] (Birmingham, Ala.) 1902-1950, 1923-01-28

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sensitive spot with the assistance of
a test buzzer. If it is. a vacuum tube,
the fflaments should be lit.- then II
one of the phone tips Is disconnected,
sharp click will indicate that the
THE is functioning.
| .. Tighten the coupling between
the primary and secondary circuits
| by bringing the primary and secon-
Diary coils in closest inductive rela-
ton. (Not necessary in the single
circuit type of receiver.)
| 8. Tune the antenna or primary
circuit. This is done by taps on the
inductance or by variable con-
denser.
| 4. Tune the secondary circuit. This
| is usually done by means of grid
variometer or variable condenser.
S. If the set is regenerative the
ticker circuit should now be ad-
1usted for a maximum regeneration
without distortion. In honeycomb
set this is done by moving the third
coil (the ticker COLD nearer to or
farther away from the secondary cir
cult. other regenerative circuits en-
ploy a variometer for this purpose.
6. In lease of interference, the
coupling should be decreased and the
, signals tuned in again, in the pri-
mary and secondary circuits, until
the interfering signal is eliminated.
In single circuit receiver, the in
ductance of the antenna circuit
should be varied and the, signals re-
tuned, with the antenna tuning con-
denser, until an adjustment is found
where the interference is reduced to
minimum.
T. If the length of your antenna is
too much lover $50 feet) connect a
variable condenser in series with the
antenna and the result will be a re-
duction of wave length, to a suitable
value.
s. If the length of your antenna
is not enough (under rs fee) 1t
would be advisable to put in either
a variable condenser across the an
| tenna inductance or a loading induct-
ance in series with the antenna in
ductance to boost up the wave length
| to a suitable value.
| 8. In a regenerative receiver it is
advisable to regulate carefully the
adjustment of filament current; if
| the filament is high, less regenera-
ton will be found necessary, and if
the filament is low, more filament
current will be required. One par
| ticular combination of these two adj
| justments will bring the signals in
with least distortion and clearest.
10. There are three methods of
| varying the Ind lctance of a coil: BY
means of taps, b. means of slider
or by means of continu lsly vari-
able inductor Sucl a variometer.
IL. Sharper tuning is accomplished
by inductively coupled tuners than
iby conductively coupled tuners, and
by two circuit receivers than by sin
gle circuit receivers.
~. Regeneration causes an effect
similar to the elimination of resist
ance from the radio-frequency cir
cults of the receiving set, and in this
way does away with energy losses in
these circuits, thus producing louder
signals.
10. A vernier condenser Ca variable
/ condenser with two or three plates)
is great help in tuning when it is
lconnected across the secondary of a
lregenerative circuit.
/ u. Distributed capacity in a tuning
coil is deleterious to sharp tuning
Shellac or varnish or any form of
wax adds to the distributed capacity
of the coil to which it is applied.
Is. The looser the coupling in a
two -circuit tuner the sharper will be
the tuning.
is. A receiving set connected to a
short, low antenna will tune sharper
than If connected to long high an
tenna. Although the latter will give
stronger results.
Turing on a loop antenna is
sharper than an outdoor antenna
this is the case with all closed os-
cillatory circuits.
4 is. The less the resistance in ar
cscillating circuit the sharper the
tuning in that circuit S
10. The use of smaller grid con
denser fsay .00025 MID. rather thar
the usual .0005 MIDI results in
greater selectivety OF tuning.
90. At least so Der cent of the eff
lciency of receiving set lies in the
} skill Of the operator who is tuning.