The Washington times., 1923-03-25
.FLIVVER RADIO WINS
IS PER CENT PRAISE
Wonderful Reception Found
Possible By Mechanism,
Expert Describes.
TESTING NEW AMPLIFlER
Excellent Results Assured Il
Fan Follows Directions
Carefully.

OdTeIullys
This Is the fourth article IN
the series describing the Flivver
RndiO. the OMt-tube receive1ag set
i,svented by E. r. FIesUeLling.
This article Is By II. j. Marc,
radio expert aUh0 has already
contributed one article to the
series.
Continuing the panel description
that was given in the previous an
ficle, sthe addition Of q two stage
audio frequency annplifier Is described
and further details ara given on the
first panel. The possibility OF
Radio frequency amplifier IL being
taken up at the present time ano
experiments are being conducted IN
order to find out whether such add;
tional stages are practical ano
whether results warrant the addi.
: ton.
!. While it is simple matter to draw
up Radio frequency stages on the
basis OF theory, still the actual
operation does not necessarily come
up to that desired at all times. Al
though q longer time win be required,
yet when results are published the
fan can feel satisfied that perform
aneR win come up to expectations e
the directions are carefully and
conscientiously carried out.
Ninety-fiVe per cent OF the letters
received on the F4ewelling circuit
praise the wonderful reception posi-.
bic by means or this receiver;
whereas but five percent complain
OF POOR reception. OF this five per
cent. the best part of the trouble
apparently is caused by lack OF suffi-
cient knowledge ofsreeeiying sets, or
poor workmanship and carelessness
in assembly of the apparatus.
DESCRIPTION OF APPARATUS.
The parts in the panel diagram are
Numbered for Identification. The
transformers, No. /, are any Of the
commercial type OF transformers
with ratio winding of about four
to one. The higher ratios are apt to
add considerable difficulty In tuning
the unit, In addition to increasing
the bowling tendency.
The vacuum tubes, No. 3, are am
plifiers and can be OF the Radiotron,
Cunningham. Myers, v To or WD-11
type. Two of the average CONNER
cial type OF filament rheostats are
required The variable leak, No. q,
is shunted across the primary OF the
audio frequency transformer and
should have a resistance range OF
one-tenth to two megohms. 1t is
impossible TO state the best value TO
be aed as. It varies considerably with
the characteristics OF the individual
h6ok-ups. After this Resistance is
once determined, II can remain fixed
and requires no further adjustment.
BINDING POST CONNECTIONS.
Eight binding posts are shown in
the diagram. The two on. the left
are for the tnput connections and
should line up with the phone bind
ing posts on the right side III The
first panel illustrated in the last ar.
ticle.s The two on the right side of
the amplifier panel are the phone
connections. The four binding posts
at the base are for the A and b bat
terry connections One of the two
in the center can be eliminated as the
Al and B. terminals Of the batteries
are connected together.
It has been found that although
the same fiiament Of A battery can
be used for both panels, satisfactory
reception with audio frequency am
plification requires a separate 100
volt B battery for simplifying stages.
For this reason the primary OF the
second transformer and the plate
circuit of the last tube, running
through the phones are both con-
nected TO this extra 100svolt plate
battery.
TRANSFORMERS NOTATIONS.
Il viii be noticed that one terminal
Of eaeh Of the secondary windings of
the trsIsf formers - Connected to the
grid Of . vacuum tale, and the other
10 tie positive "a battery circuit.
-, 80 zaSi article attention was
80 70 the. fact that when the
s,.i..S u The transformer is sub.
a. a. "a tor the nead phones, the
H. Srcnt . unbalanced and
S,e s~ ~ f1sak. No. 81 in that circuit
t,r - readiUs tment. The inser-
az ss0f the variable leak, No. 4,
e the primary Of the first audio
ency simplifying transformer
q za balance Ibis condition and re-
- considerably the necessary re-
ii1-isment Of the detecter circuit.
Il LNG OPERATION.
kre at smpting to use the am.
piif5 -ag stages, the amateur should
become thoroughly acquainted with
the opera ION Of tuning of the first
unit. as the addition of simplifying
stages increases the necessary criti-
cal adjustments. When the audIo
frequency unit is connected to the
first unit and the phones connected
10 tfie binding post on the right side,
n wiil be found that the set In
especially noisy and has a decided
whistling.
This noisy tendency is first re-
duced by means of the variable leak
across the primary of the transform
err until the point of minimum noise
IS found. Note that the adjustment
is merely to reduce the noise to a
minimum, as further elimination of
the whistling must be accomplished
through the deteetor circuit readjust-
ment.. Even then, entire elimination
OF the whistling requires filter.
The whistling is controlled by. re-