The Monmouth inquirer. [volume] (Freehold, N.J.) 1865-1933, 1926-03-04
By EDWARD sPIEoLER,
York Herald Tribune.

For dependable, trustworthy radio
broadcast receiver, one that will work
consistently night in and night out
without fuss or bother, the writer be-
lieves 1t is difficult to find one more
desirable than a straight five-tube,
three-dial tuned radio-frequency set
constructed with efficient condensers
and tuning coils and equipped with
standard accessories. The sensitive
ness. selectivity and volume Of an
outfit Of this type can be practically
guaranteed in advance. and the build
er can be assured that he is not
spending his money on some ones
notion of freakishly different" re-
ceiver Of undetermined worth. When
he has finished the wiring and con-
nected the batteries he will hear
broadcasting, and hear it well.
The writer recently completed such
receiver, incorporating in 1t the
acceptable innovation Of few new
tuning inductances, and enjoyed an
instant satisfaction from it that was
unusual He had previously made a
number OF popularity exploited radio
frequency sets of different design, and
had spent whole evenings of patient
adjustment on each In an effort to
obtain good results. This orthodox,
unpretentious outfit, Boosting moth
ing more radical than some straight
line frequency condensers and some
different r. F. coils, produced such
immediate results in the form Of many
and loud stations that he thinks peo-
pie who want fool-proof receivers
should be told about 1t.
Parts Required.
The average constructor will have
no difficulty in assembling the set with
the aid of ordinary hand tools. The
parts required are a panel by "a
inches, of any good insulating ma
terial; a half-inch thick wood base
board Of the same dimensions, three
Gen-win Lemnis coils, three .0O035
MID. strajght-line frequency condens-
ers, three dials to fit same, one six,
and one thirty-ohm rheostat, one
double and one single circuit telephone
Jack, five standard tube sockets, grid
condenser and leak, two audio-fre-
qUency transformers, one battery
switch, one binding post strip and
the usual busbar and other incidentals.
The set is most conveniently as
sembled in two units, the panel and
the Dashboard.
The sockets for the r. #. tubes oc-
cupy the space between the variable
condensers and little to the rear of
them. The detector socket is up in
the extreme upper right corner of the
Dashboard, and is followed by the A.
r. transformers and tubes winding
along the back edge of the board. The
second A. f. tube is In the upper left
SECTION, its ''P" post going convenient
y 90 the telephone Jack in the lower
left corner of the panel. Similarly, the
right-hand Jack connects to the adj
j¢ detector socket.
This U-shaped layout keeps all the
connections very short and In their
logical order.
About 80 per cent of the wiring in
viewed in the construction OF this
receiver can and should be done on
the Dashboard instruments before the
panel is screwed into position. The
constructor is advised against as
sembling the parts first and wiring
afterward, as the presence Of the pro-
tyuding variable condensers win make
tie installation of many of the wires
exceedingly difficult.
No binding posts are provided for
the ''C'' battery, as this unit is most
easily connected by means Of short
lengths Of flexible cord. The other
battery connections are standard and
are easily followed.
The Wiring.
The wiring Of the r. f.. and A. r.
stages is more or less orthodox IN
nature. The three variable condensers
are connected directly across the re-
spective secondaries Of the Lemnis
coils. with stationary plates going to
the grids of the tubes and rotary
plates to the filament circuit.
The feature of this receiver, outside
OF its general effectiveness. is the type
of radio-frequency tuning units EN-
ployed Each one consists of a IL
turn primary and a 1O3-turn second
AIRY, the wire being wound according
to the lemniscate principle. This form
confines the electromagnetic field and
neutraIizes the tendency toward oscil-
iation. The extraordinary length Of
the lemniscate curve reduces the re-
sistance otherwise encountered in
small diameter coils.
The wire used is No. 20 enameled,
high turn-to-turn capacity being
avoided by system Of spaced wind
ing. Over all, coll is just three
inches long and two and three
quarters across the loops; the small
diameter Of the latter is one inch.
An ingenious experimenter can