Radio Broadcast - 1925, February - 113 Pages ... - VacuumTubeEra

:
726 Radio Broadcast
From the binding post marked " +A" run a
wire to each socket terminal marked " + F".
From the binding post marked " A" run a
wire to one terminal of the filament switch.
From the other switch terminal run a wire to
one terminal of each rheostat. The other
three terminals of the rheostats are connected
respectively to each socket terminal marked
"
F". The filament circuit is now completed.
As each wire is
put in place
it is well
to mark it off on the circuit diagram with a
red or blue pencil.
The antenna-grid circuit is wired as follows:
Run a wire from the tuner terminal marked
WOODEN SPOOL FORM
FOR
RADIO FREQUENCY
TRANSFORMER
FIG. 3
F&B
WINDING
STYLE
Constructional and winding details o.
the special radio-frequency transformer
"LA" to the left hand binding post which
should also be marked "LA" (long antenna.)
Run a wire from the terminal "SA" to the
binding post to the right of the one marked
"LA." This binding post should be marked
"SA" (short antenna.) Then connect the
terminal marked "GND" to the binding post
to the right of the one marked "SA." This
binding post should be marked "GND"
(ground). This completes the antenna-ground
connections. The grid circuit is wired as
follows. Connect the tuner terminal "C2"
to the stationary plates of your thirteen or
seventeen plate condenser, and connect the
terminal "Ci " to the rotor plates. Then run
a wire from "C2" terminal to the first socket
terminal marked "G". Connect the tuner
terminal marked " -A" to the secondary
terminal of the high ratio audio transformer
marked "G." The "F" terminal of this
transformer secondary is
joined to the wire
from the " A" binding post. A small fixed
mica condenser (.00025 or -0005 mfd.) should
be connected across the secondary terminals
of this audio transformer. There remains
only the compensating condenser, the rotating
plate of which is connected to the first
socket terminal marked "P" while the stationary
plate
is connected to the tuner terminal
"Ci ". This completes the grid circuit.
All these connections are clearly shown in
Fig. 2 together with the general shape of the
wires, and by following the drawing the problem
becomes fairly simple.
The reflex circuit is wired as follows. Connect
the first socket terminal marked "P"
to the "P" terminal of the radio-frequency
transformer. The " B " terminal of this transformer
is connected to the upper terminal of
the double circuit jack. The bottom terminal
of the double circuit jack goes to the binding
post at the extreme right and should be marked
"+B". A fixed mica condenser C^ of .005
mfd. capacity should be connected across the
two outside terminals of the double circuit
jack. From the "G" terminal of the radiofrequency
transformer, run a wire to one end
of the fixed detector. The other terminal of
the fixed detector is connected to the primary
terminal of the high ratio audio transformer
marked " P." The " B " terminal of this audio
transformer is connected to the "F" terminal
of the radio-frequency transformer. The reflex
circuit is now completed,
From the double circuit jack terminal next
to the top, run a wire to the low ratio audio
transformer terminal marked "P." The remaining
double jack terminal is connected to
the " B" terminal of the low ratio transformer.
Join the "G" terminal of this transformer to
the second socket "G" terminal and connect
the "F" terminal of the transformer to the
wire coming from the " A" binding post.
Connect the "P" socket terminal to the bottom
terminal of the next double circuit jack. The
top terminal of the second jack goes to the
'+B" binding post. The wiring
is completed
by connecting together the binding
posts marked " B" and " +A."
ADDING A
COONER or later,
PUSH-PULL AMPLIFIER
into the life of every
^ real
radio fan comes the desire for more volume
and then comes the hunt for a means of amplification.
Though both the one-tube and the two-tube
units of this reflex circuit afford good volume
on all
average reception, there are many who
want more. But how to get this additional
volume has been more of a problem than would
at first glance appear.