Evening star., 1924-05-09
FIFTEEN MINUTES
OF RADIO EACH DAY
BY JOSEPH CALCATERRA.
Radio Editor of Popular Science Monthly.
ALI Rights Reserved. Reproduction Pro-
hibited.
How to Build n FOur-Tube Superdyne
Receiyer-Part ".

Receiyer-Part Nv.
Now for the last lap in making
the connections.
Connect the A terminal of fixed
condenser % with the G. terminal of
socket 25 according to illustrations
appearing previously with this series.
Then connect the p terminal of socket
25 with one of the outside springs
(A) of jack 13. The P terminal of
transformer 81 should be connected
with the inside spring that makes
contact with outside spring A Gn this
case b. The d terminal (the other
outside spring. of jack IS is connect
spring G, which makes contact with
outside spring D, is connected with
terminal B of transformer 27.
Now run wire from the G ter
nninal of transformer 27 to the G
terminal of socket IS. The outside
spring A of jack II Of corresponding
to the spring of jack 13 is then con-
nected with the p terminal of socket
IS. The inside spring, which makes
contact with outside spring A, is con-
nected with the p terminal of trans
former 81.
The other outside spring d is con-
nected with spring B of jack IS and
with binding post 80. The inside
spring c of jack II, which makes
contact with outside spring ID. is con-
nected with terminal b of trans
former 81
Now connect the G. terminal of
transformer 81 with the G terminal
of socket 80. Then connect the p
terminal of socket 80 with spring A
of jack IS.
Connection of Leads.
Leads from the + terminals of
fra ST 2T and RI are connect q
with the negative 3 or AS volt ter
minals of the c battery and left
where they give best results.
This completes the wiring of the
receiver.
For best results it is advisable to
use the wv 201A or c 301A types of
tubes. Very good results, however,
can be obtained by using the wv 199
tubes or c 299 tubes.
I am going to caution you again
here to follow out the directions re-
garding the size of windings and the
distance between the Stator and rotor
coils of the variocoupler. This point
is vary important one and failure
poor results.
The A battery used will OF course,
depend on the tubes employed in the
receiver. The B battery should have
voltage of 80 volts. If a soft tube
is used as a detector the B battery
higher than 22.5 volts for the plate
circuit of the detector-that is, bind
ing post 26 should be connected with
the 22.5-volt tap. If a hard tube. such
as the wv 1873 or Nv 201A tube, is
used as a detector a B battery volt
age up to 67.5 can be used Binding
post 81 should be connected with a B
battery voltage of from 45 to 80
volts Binding post 80 should be con-
nected with the 90-volt terminal of
the B battery.
Operation of Set.
The operation of the receiver is
rather difficult to describe in writing.
A little practice will do more than all
the explanations in the world in CIV
ing you a working knowledge of its
operation. The rough wave length
setting is obtained by means of the
two switches. The finer adjustment
for tuning is obtained by means of
the variable condenser adjustments.
The adjustment of the ticker, coil 6,
StabilizeS the circuit and prevents the
circuit from going into oscillation
when the plate and grid circuits of
onance, condition which would
produce oscillation if it were not
for the stabilizing action of the
tick1er coil
If after you have tried the circuit
you find that it is rather difficult to
control you may try reversing the
connections to the secondary coil 5,
so that the grid side of the circuit is
connected with the bottom end of
| the winding-that is, the end marked
42-and the f1lament side is connected
with the top end of the coil marked O.
When the circuit is finally COM
pleted the results obtained will more
than justify its construction. Do not,
however, expect to get best results
and most efficient operation if you do
1yrnn md he
seemingly slight changes which ]
have mentioned.