Belt Valley times. [volume] (Armington, Mont.) 1894-1977, 1926-02-25
eY CARLTON 6. eurLER.

Member American Institute OF Electri-
cal Engineers and Institute of Radio
Engineers.
Changing conditions make new
radio circuits necessary. A few years
ago the single circuit and ultra
audIon receivers were satisfactory
and were capable of bringing In dis
tant stations with volume. To-day the
same sets cannot be used, except In
Isolated districts away from broad
casting stations, due to their broad
tuning qualities.
The receiver OF the earlier day is
no longer satisfactory for other rea-
sons. principally on account Of its
squealing and radiatIng qualities and
because It's tone quality Is poor and
distorted. AT the last radio confer
enee In Washington 1t was agreed that
In the near future the use Of radlating
receivers would have to be ended, even
II It became necessary 10 pass q fed
eral law to accomplish that result.
Today, with modern laboratory
standard apparatus available, and
with sets OF better design, the quality
attaIns the standard demanded by
lovers Of music.
The R-4 circuit. as developed for
use In new receiving set, is good
example OF present day design. The
most popular form OF circuit was
selected-the Ave tube tuned radio
freaHeHey-and by the=us Of the lat
est type OF condensers, coils, and
transformers, together with improve
ments in the circuit, produced re-
ceiver that Is capable Of tuning
through interference, bringing in sta
tions from a distance on the loud
speaker, and surprising many re-
celvers for all around performance
and quality of tone.
To shut Out stray Currents.
Noteworthy OF the improvements In
the circuit are two bypass fixed con-
densers. between the primary OF each
OF the first two radio frequency trans
formers and the filament. This serves
to bypass and keep stray radio fire.
quency currents out OF the rest Of the
wiring, and stablllzes the circuit A
large condenser is placed across the
ssBa battery terminals to reduce noises
and bowls due to long leads or low
voltage
Rehnements in apparatus include
the new square wound toroid coil.
with the new straight line frequency |
which provide shielding OF
lines Of force, as well
as keep the instrument dustproof
mighty important detail.
The toroidal coils eliminate the
spraying effect OF magnetic lines OF
force within the set proper, and re-
move the principal bugbeHr that radio
engineers have been working for years
to solve. The coils have self-con-
tanned fields that make pickup Of stray
current impossible. Their use In the
R. receiver makes a set that will
June through strong interference
The variable condensers on the FIRST
md second stages OF radio may be
.uned by one control as IN the manu-
'actured receiver II desired. Three
and three dlals may be
Used in the ordinary manner. how
,Yer, without lessening efficiency.
The Parts Needed.
To construct the circuit you Will
iced the following parts:
Square wound toFoid coll, type
Il indicated on diagram as Ii.
2 Square wound toroId coils. type
y indicated as LIZ and rs.
straight-llne frequency variable
ondensers. preferably the AII-Ameri-
an shielded type C35. indicated on
IagraBa as CT, CT CT, and t55a3.
2 Rauland lyric audio transform
r.. type R500.
8 yOO2 mid. fixed condensers. in
lcated on diagram rs ca. C5 and Cs.
1 .OOO25 mid. fixed condenser, In
Icated on diagram as CO.
/ 10 MID. fixed condenser, in
Icated on diagram as CT.
The rheostats should each be Of
x ohms capacity for the use Of Nv
DI-A or c COLA tubes. and the grid
ak R3 should be two meg0hms. When
sing the new UX ampliher tubes, /.
reak the grid return Of the last 4
ansformer and insert &C. battery OF =
oItage recommended by the manu- Il
Icturer. q
The hrst rieostHt Is used as a 4
olume control, to moderate signal 4
rength to the desired extent For B,
ost satisfactory operation, the cor Fl
,ct setting Of this control may be q
stermined by trial. and then allowed 81
remain without further adjust A
emf.
In addition TO the apparatus named
Dove. you will need five sockets.
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