New-York tribune., 1922-07-16
Armstrong;
Radio Fliyyer
Is Described
Value of Parts Used i'm His
Remarkable Adaptation of
Epoch-Making Super-Re-
generafive InventionCiven
Uses Only / Vacuum Tube
Which Acts as Regeneration
OscilIafor, Detector and
Amplifier simultaneously

wizard of radio, demonstrated his lat
est invention before the Radio Club
Of America he astonished his audience
ny producing the super-regenerative
tate with a single vacuum tube. In
this demonstration he filled the large
lecture room with music from the W.
J. z. station at Newark with loop
serial in building of steel construc-
ton rooted with copper.
So completely surprised were those
present in the audience that they i'm
nediately gave vent to their feelings
IN burst of applause. AS soon as this
ed down Major Armstrong said:
"The super-heterodyne system using
scven tubes is the Rolls-Royce of radio.
There are people who can ride in Rolls
oyce cars, but the majority have to
de in Fords. 1t is just the same in
the super-heterodyne, but this is the
Ford of radio"
Details Given for First Time
Since then radio fans throughout
the country have been anxious to get
the circuit and constants of this re-
markable system, and they are repro
tuced herewith for the first time. The
diagram which appears this week
SHOWS every part needed in this set,
together with the values.
The wonderful thing about this cir
cult is that under the arrangement a
single vacuum tube performs slmul-
taneously the functions of regenerator,
oscillator, detector and amplitier. The
fesults obtained from it using loop
serial are equivalent to the regulation
regenerative receiver with two stages
of audio frequency amplification, used
in conjunction with the best possible
aerial under the most ideal circum-
stances.
Although these results are truly
stounding, the circuit requires very
careful handling by the experimenter,
who will have to learn the delicate
adjustments by experience, and the
probability is that the proper results
will not be obtained for quite little
while.
Four Methods in System
There are four methods by which
,Iajor Armstrong succeeded IN OBTAIN
ing super-regeneration. In this one
it is accomplished by the simultane-
Gus variation of the positive and mega
tive resistances of the circuit. This
is achieved by means of the second
ceed-back circuit (shown in the dia-
Gram under the numbers 13, IA, 10 and
l6), which is adjusted to oscillate at
y lower frequency than the incoming
signal The proper phase relations be-
tween the negative and positive re-
distances are obtained by adjustment
# the condensers 13 and 16 and the
COUPLING between the coils Ia and ID.
1t will thus be seen that the two
large duo-lateral coils IA and Is must
he in an inductive relationship to each
other 1t will be found that this re-
lationship is very critical, and the
greatest possible care must be eXer-
csed in adjusting this relati onship, as
we'll as obtaining the correct amount
If capacity in the two condensers l3
and 1e.
Although these two condensers are
hown as variable in the diagram, they
90 not necessarily have to be of the
iegulaton variable air condenser type.
They can be made up of a number
Of fixed condensers connected in paral-
lei with each other and so arranged
to multi-point switches that any one
of them can be brought into or taken
out of the circuit. In other words,
they can be made variable in steps.
How Loop Aerial Is Made
The loop aerial can be constructed
en- a square frame three feet long on
each of the four sides. The wire can
be wound around this frame either in
solenoid or spiral fashion. If the
former there should be ten turns, each
spaced quarter of an inch apart, and
If in the latter form there should be
twelve turns, each spaced a quarter OF
an inch apart. Number 18 cotton-cov-
cred bell wire can be used.
The loop is connected across the
primary of the ario-coupler-which is
shown in the diagram as coils 8 and g
he 70
length of the incoming signal is done
by means of the condenser number 4
The secondary of the vario-coupler
should have about twice the number
Of turns it normally has when used
for ordinary purposes.
The grid battery shown in the da-
gram as No. S consists of two pocket
fashlight cells Joined in series, giving
n total of approximately four volts
The negative terminal of this small
battery must be joined to the grid
The filter system is the same as that
recently shown in these columns with
the three-tube uper-regenerative
circuit
Resistance and Choke Standard
The $4,000 ohm resistanees and the
100 mlli-henry iron core choke coil
are standard instruments used for
filter purposes in telephone repeater
circuits, and they can be obtained from
stores handling telephone supplies
They will undoubtedly be on the mar
.ket in quantities in the near future.
Condenser No. s can be built up of
fixed units in the manner described
for condensers 13 and 16.
In this particular circuit it must be
remembered that there are seven criti-
cal adjustments to be made. This is
the price that has to be paid in getting
one vacuum tube to perform four sep
crate and distinct functions success
fully. This fact is not stated to dis
courage the experimenter, but to inn
press upon him the Importance of very
delicate and careful adjustment. Il
will also serve TO remind him that in
the event of failure at the first time
success can be obtained only from
complete mastery of the adjustable
parts of the circuit. The subsequent
results will amply repay the trouble.
For experimenters who are some dis
tance from the broadcasting station a
single stage of audio frequency ampli-
fcation can be added to this circuit in
tie manner shown in the diagram
printed in this paper on July 2, when
the three-tube super-regenerative cir
cult was given. The leads to the am
plifying transformer primary will be
placed where the telephones are shown
in the present diagram.
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