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Radio News for November, 1928 459
SET BUILDING IN FRANCE
Editor, RADIO NEWS:
Just a few lines of appreciation to yourself and
RADIO NEWS, the current copy of which was a
boon companion to me during an exceedingly violent
electrical storm up here (at Holzleck, in the
Vosges Mountains). I was far too deeply engrossed
in your description of the Screen -Grid Strobodyne
to notice such trifles as storms. I ha n
taken RADIO NEWS since its first edition but, because
of traveling all over the world, I had to
plan with my newsdealer in New York to hold
over my copies until my return. Now that I have
a permanent address in Paris, I have at last become
a subscriber.
Here is something that would be of great assistance
to me and undoubtedly to many other
fans over here, and that is a table comuaring the
relative sizes of wires between the American B & S
gauge and the French gauge which is given in
mils. I desire to build a Strobodyne a l' Americaine,
but cannot do so until I know what size
wire is equivalent to that given. (See below). I
fell down on the construction of the RADIO News
Short -Wave set on this account and am anxious
to complete it and fish for good old \VRXY on
the 30.91 -meter wave.
We have not yet come to the screen -grid tube
in France, but I have found that the "Metal
Radio" factories are putting one on the market
in the near future, and if it has similar characteristics
to the 222, I shall build the Strobodyne
S. G. as described.
I am at present using a Strobodyne built by M.
Chrétien, the originator of the circuit, but the
American hook -up is way ahead of it. My set
has coils for both wavebands (180 to 500 and 500
to 3.000 meters) incorporated, and the change is
made by a commutator on the panel.
By the way, the relay of the Tunney- Ilceney
fight over Daventry and 21.0 was wonderful. I
received it in Paris clear as a bell. Absolutely
no fading right up to R'GY's announcement of
the time signal, when England acknowledged the
defeat of her champion with silence immediate and
profound. But that relay certainly spoke worlds
of the future of radio from an international view -
point; may good old RADIO NEWS stick and grow
with it..
R. W. HuMPHRE.YS,
57 Boulevard Suchet, Paris 16e, France
Metric Measurements of Wire
( Fiere arc the measurements of copper wire -
the metal conductor only -in the metric system: the
diameter in millimeters and the area in square
millimeters. This may be of benefit to some of
our other friends abroad. The gauge is Use familiar
American Brown & Sharpe.- Eotroa.)
Gauge Diam. Area Gauge Diam. Area
14 1.628 2.081 28 0.321 0.081
16 1.291 1.309 30 0.255 0.051
18 1.024 0.823 32 0.202 0.032
20 0.812 0.513 34 0.160 0.020
22 0.644 0.325 36 0.127 0.013
24 0.511 0.205 38 0.101 0.008
26 0.405 0.123 40 0.080 0.005
NO PANCAKES FOR BREAKFAST
Editor, RADIO NEWS:
I attach a snapshot of two speakers made of
scrap paper, a cone and a horn built along the
lines of the model described in Chester Schenck's
article in the June issue of RADIO NEWS. The
horn was built around a form made from an old
orange crate and some stiff cardboard; the forni
Mr. Ste-wart, above, flanked on either side by
a low -cost loud speaker made as described.
It will be bard to lower his record unless you
steal a unit.
being well coated with talcum powder to insure
its easy removal after the horn had thoroughly
dried. For the material, I used all the old magazines,
newspapers, wrapping paper and so forth
that was available, and for paste a mixture of flour
and water. The job was rather tedious; but, as
L am not especially fond of work anyway, it came
in handy to apply a layer or two a day and allow
time for drying. The horn was finally built up to
near / -inch in thickness, but is still too thin. Only
one brace is used, that being made of four pieces
of wood, )1 -inch square and about twelve inches
long, nailed together in the form of a square and
slipped down on the bell as far as it will go and
pasted in position. The tone is as good as that of
several manufactured horns I've heard, and better
than some.
The cotte consists of one layer of heavy brown
wrapping paper with two layers of newspapers
pasted on the outside, three layers in all. A circle
36 inches in diameter was laid off out this and a
V- shaped slice cut out. That gave me a cone 34
inches in diameter and 7 inches deep. A loop of
soft copper wire was pasted on the outer edge and
the string used for mounting the cone in the
square wooden framework was laced back and forth
through the wire and to the frame. A 1 x 2
bolted to the frame, supports a cigar box, which,
in turn. supports the driving unit, one taken from
a Musicone. The main item of expense in this big
cone was five cents for the two bolts in the 1 x 2;
the flour for the paste was stolen from the family
larder, so cost nothing.
The cone is by far the better of the two. Both
reproduce well the bass and middle- register notes;
but we have lots of static down in this hot country
and it is not so objectionable on the cone as on
the horn. The set driving these speakers is home -
built, a Browning -Drake type, with a screen -grid
R.F. stage, 200A detector, Thordarson Autoformer
audio amplifier with a UX -112 in the last socket.
\ olume amt quality de luxe!
GtY STEWART,
U opio, Texas.
A SENSITIVE FOUR -TUBER
Editor, RADIO NED S:
I am sending my four -tube circuit, which was
very much like Mr. McCormick's till the screen -
grid tube came out. I think that the only real
difference was that I changed my antenna coil
by doing away with the fixed condenser and tapping
at the twelfth turn from the filament end. 1
have written Mr. McCormick, advis'ng him to put
a screen -grid tube in his R.F. stage; it requires
only a little changing and it is well worth the
trouble. With his DX record, using a 201A, he
certainly should step out with the screen -grid hookup
for a few more miles.
This circuit is very sensitive and selective with
a short antenna, and the west coast comes in with
plenty of volume.
We have only from 7:30 p. m. until midnight
to do any DXing, on account of the high -power
naval station NSS here, which sends off a heavy
mush or "back- wash "; so you can see ive do not
have a shot at the foreigners. My most distant
stations are California, Mexico, Cuba and Canada;
but remember we have to do this early.
This circuit was originally the "Reactodyne" published
by RADIO NEWS its 1924. I hope you can
interest a few others in this circuit.
FRANCIS E. ENGLE,
14 Cathedral St., Annapolis, .l(d.
A SINGLE- CONTROL SHORT -WAVER
Editor, RADIO NEws:
I am enclosing a diagram of a "one-hand" shortwave
receiver I have been using for about four
months. I use Aero short -wave coils; with this
arrangement I am able to set the feed -back control
condenser for a given coil and sweep th,s whole
range without any other adjustment until the desired
signal is found. Then a little adjustment of
the detector filament and I am all set to listen.
No more "holes," etc.
I am using special R.F. chokes. \\'hile an
Aero No. 10 will work very well, a choke with very
low inductance must be used on S. W. I use No.
36 S.C.C. on a piece of round or square Vs -inch
bakelite, about 6 inches long; start winding otoz
end about 40 turns, space %-inch, then 60 turns,
space 1/s -inch, 80 turns, and so on till the space is
used up. I find the 112A tube the best detector
for this receiver; the rest is standard.
W. E. SMITH,
Oak Forest, Illinois.
MR. LOVELESS IS NOT SOLELY TO BLAME
Editor, RADIO NEWS:
I was interested in finding in the article on the
Loveless aerial the description of a circuit embodying
the principle of my patent No. 1,668,261,
issued to me by the patent office May 1, 1928;
application for the same having been filed Dec. 27,
1923. An examination of this patent will reveal
the validity of my claim; for it will be there seen
that specific claim is there made for aerial circuits
together with a claim embodying the same principle
in radio sets themselves. The discovery of the
principle involved was made by me as far back
as 1920, while engaged as professor of physics its
the University of Santa Clara.
(Rev.) RICHARD H. BELL, S. J.
St. Ignatius College, 2130 Fulton St.,
San Francisco, Calif.
(Continued on page 498)
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Mr. Engle's hook -up differs from the " Reactodyne" in its aerial circuit; the latter was
very loosely coupled in the original. The primaries are wound fumble -fashion and placed
inside the secondaries, which are on 3 -inch tubing. Transformers are 5.31 220s. Ile
suggest a fixed ballast also in the 222's "A-."
Mr. Smith's set is tot a reflex, as first glance might suggest,
but a short -waver with two A.F. amplification stages.
Our readers may test it to see if ease of operation is accompanied
by necessary sensitivity and control.