stations have been located, however, it may be possible to increase
the volume and to better the tuning slightly by a careful
readjustment of the drums until the best reception is obtained.
If
no signals are heard while tuning, various positions
of
the
loop should be tried. For every station there is a position of the loop
which will give best reception.
Control of Volume.
As Radiola 25 is a very sensitive
receiver, it is usually necessary to use only a portion of its full
power. The loudspeaker output may be reduced by using one or
more of the following methods:
(1) Turn "
FILAMENT
"
pointer to the left. This decreases the
volume by reducing the filament temperature, thus prolonging the
life of the Radiotrons. The pointer should, however, be set far
enough to the right to maintain a good quality of reproduction.
(2) Turn "
VOLUME CONTROL
"
pointer toward "
SOFT
".
(3) Insert the telephone plug into the first stage telephone
jack H (Fig. 13).
(4) Rotate the loop until the best position is found.
(5) On powerful near-by stations an additional reduction is
often necessary. This may be obtained by holding the right-hand
station selector drum firmly in position and moving the left-hand
drum a few divisions either forward or backward until the desired
intensity is obtained. Note that the new position of the left drum
affects only the intensity or volume of the signal, while a slight
change in the position of the right drum affects the quality of
reproduction. Therefore the right-hand drum should be adjusted
with extreme care.
Interference.
Signals from an interfering radio station may
be eliminated, or at least minimized, by either of the following
methods:
(1) While holding the left-hand drum
G,
rotate the right-
hand drum N forward or backward by approximately 10 scale
divisions to find another position of this control, where the
desired station will be again heard. The setting of the right-hand
drum nearer the 0 end of the scale is technically called the "lower
frequency peak," and the other the "upper frequency peak." Two
settings of this nature will be found for all broadcasting stations,
and the separation between them will be found approximately the
same throughout the whole length of the scale.
It
is recommended
that the right-hand drum N be consistently set at the "lower peak"
in the manipulation of Radiola 25. (When this is done, the gradu-
ations showing the settings of the right-hand drum will
correspond very closely with those of the left-hand drum.)
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