RadioBroadcast-Vol-12-1928-01.pdf

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RADIO
BROADCAST
How
to
Use
the
Screen-
Grid
Tube
A
Directory
of
Manufactured
Receivers
Hints
CooleyRayfoto
Receive
onOperatincftour
The
Phonograph
Joins
tKe
Radio
Receiver
A
Push-Pull
Amplifier
and
B
Supply
Inside
the
Complete
Receiver
i
35
Qmts
'X^
r
p
Vitv.
jVew
Uork^
JAN
-*9
2
-J
RADIO!
SINCE
1915
CUNNINGHAM'
TUBES
STANDARD
f
OR
ALL
SETS
;cx;|oi-A
gifts
that
bring
happiness
at
Christmas
time
and
throughout
the
year
Radio
sets
and
radio
equipment
make
immensely
popular
Christmas
gifts.
assure
the
utmost
in
Yule-tide
Radio
enchantment,
see
that
Cunningham
Radio
Tubes
are
on
duty
in
every
socket.
Every
To
owner
of
a
radio
will
be
delighted to
re-
ceive
a
set
of
new
tubes.
Buy
them
Your
in
combination
of
five
or
more.
I
you
the
correct
types
of
Cunningham
Radio
Tubes
for
which
any
radio
set
is
designed.
Don't
use
old
tubes
with
new
ones.
dealer
will
tell
Use
new
tubes
throughout.
E.
T.
CUNNINGHAM,
Chicago
Inc.
New
York
San
Francisco
RADIO
BROADCAST
ADVERTISER
191
Power
Improve
Reception!
ft
ELECTRAD
Certified
Quality
Lead-ins
Eliminate
insulation trou-
bles
at
the
entrance
point
of
your
aerial
and have
bet-
ter
reception
by
using:
this
superior
constructed Lead-in.
Bends
any
shape
to
fit
around
the
corners
and
under
locked
doors
or
windows.
Triple-ply
insulation
full
10
inches,
covered
with
water-
proof
webbing.
One
piece
copper
strip
heavily
tinned
to
prevent
corrosion.
Protect
yourself
by
looking
for
the
Electrad
name.
Price
40c
each.
At
your
dealers.
Write
for
Descriptive
Circulars
Dept.
61B,
175VarkkSt.,
\ PUSH-PULL
amplifier
in
that
**
power
to
sustain
a
high
volume
last
stage
level
provides
the
speaker
with
ample
without
tube
overloading,
transmit-
New
York,
N.Y.
ting
the
full
effects
of
large
swings
in
intensity
common
in
orchestra
music.
ELECTRAD
fROST-RADIO
OFFERS
RADIO
BROADCAST
READERS
TWO
VALUABLE
NEW
BOOKLETS
FREE!
WE
^*
request
:
This
balanced
type
of
amplifier
draws
no
alternating
current
from
the
plate
supply,
a
fact
of
great
importance
if
socket
power
is
used,
as
the
impedance
of
the
power
unit
does
not
affect
the
amplifier.
This
results
in
improved
re-
production
of
sustained
notes,
particularly
of
low
frequency.
Other
advantages
of
the
push-pull
system
are,
a
reduction
in
hum
when
al-
ternating
current
is
used
for
filament
supply
and
for
equal
power
outputs,
a
reduction
in
the
plate
voltage
required.
The
Type
amplifier
is
supplied
completely
wired.
Write
for
Them
OFFER
readers
of
Radio
"What
Set
Broadcast
two
valuable
new
Frost-Radio
publications
free
on
Shall
I
Build?"
the
answer
to
a
question
which
puzzles
many
set
builders,
and
the
new
Frost
booklet
"For
Better
Reception,"
a
complete
and.
Frost
Parts.
helpful
manual
of
Every
set
builder
should
have
bmii
of
these
booklets.
They
will
be
found
chock-full
of
useful
infor-
mation
that
is
right
up
to
the
minute.
For
use
with
UX
226,
CX
326,
UX
171,
CX
371,
UX
210,
or
310
tubes.
Input
inductance
30
henries.
i
Input
turns
ratio
:2.25.
Output
impedance
ratio
12:1.
(whole
primary
to
secondary)
Price
completely
wired
$20.00.
441
amplifier
CX
FROST-RADIO
What
they
Contain
newest
and
circuits
most
popular
"For
Better
Reception"
tells
you
proper
size
rheostat
for
mill
nil"
has
wiring
sets,
dlnRfHins
for
high
resistance
the
1
telK
"What
S.-t
Shiill
much
about
I
Build?"
Licensed
by
the
Radio
Corporation
of
America
for
radio
amateur,
experi-
mental
and
broadcast
reception
only
and
under
the
terms
of
the
R.
C. A.
license
the
unit
may
be
sold
only with
tubes.
1
i
and
unit,
facts
about
contains
valuable
Frost-Radio
Parts.
FROST-RADIO
GENERAL
RADIO
NOW
I
Mail
Coupon
To
secure
>ok
these
t
wo
lets
nil
out
and
mail
coupon
below,
printing
your
-
FREE
LABORATORY
EQUIPMENT
PARTS
If
for
name
and
address
with
Write
their
for
carefully.
These
books
will
amaze
you
NOW.
completeness.
them
to-day
and
ACCESSORIES
A
supplying
technical
correspondence.
Write
of
amplification
booklets
describing
in
HERBERT
Inc.
H.
Elkhart,
FROST,
Indiana
HERBERT
160
I'ltMx-
North La
send
fMSTRAMO
H.
FROST,
me
Chicago
New
Vork
as
information,
we
can
be
of help
to
you
we
welcome
your
our
Series
Inc.
Salle
Street,
Chicago
free
your
two
for
January.
various
amplifiers,
circuits
and
units.
advertised
In
booklets,
Radio
Broadcast
Name
Street
GENERAL
RADIO
Address
State
.
.
CO.
Cambridge,
Mass.
City
RADIO
BROADCAST
WILLIS
KINGSLEY
WING,
Editor
JANUARY,
1928
KEITH
HENNEV
Director
of
the
Laboratory
EDGAR
H.
FELIX
Vol.
XII,
No.
3
Contributing
Editor
AMO^G
OTHER
Cover
Design
Frontispiece
-
THINGS.
.
.
*.
'
-
From
a.
Design
by
Harvey
Hopkins
Dunn
194
195
198
In
the
Laboratory
of
a
Tube
Manufacturer
duty
to
record
the
death
of
the
Chairman
of the
Radio
Commission,
Admiral
W.
H. G.
Bullard,
which
occurred
in
Washington
on
Thanksgiving
Day.
Admiral
Bullard,
who
served
in
the
United
States
Navy
for
thirty-six
IS
a
sad
IT
Federal
Radio
Enlists
the
Helium
Atom
-
Volney
G.
Mathison
The
March
Can
of
Radio
An
What
a
Editorial
Interpretation
Say
the
Serious
Problem
of
Radio
Patents
Be
Settled?
The
Prospects
of
a
Patent
Pool
Readers
Conditions
About
Broadcasting
years,
for
a
very
long time
was
close
to
the
center
of
radio
in
almost
all
of
its
branches.
His
loss
will
be
keenly
felt,
not
only
by
those
who
knew
him
as
a
likable
and
able
individual
but
especially
by
the
Radio
Commission
itself.
When
the
Radio
The
Commission
Announces
The
Commission
Suggests
Schemes
New
Policy
Synchronization
Broadcasting
Bands
Changed
Broadcasting
Notes
News
of
the
Patent
Field
Among
the
Manufacturers
Push-Pull
Amplification
Why?
-
Howard
E.
Rhodes
202
The
Phonograph
Joins the
Radio
Set
206
Keith
Henney
Commission
went
to
work
on
March
15,
two
of
its
members
had
a
background
of
technical
radio
experience.
These
two
men
were
Admiral
Bullard
and
Colonel
Dillon.
Death
has
removed
both.
The
Commission
at
this
writing
now
consists
of
Acting-
Chairman
E.
O.
Sykes,
O.
H.
Caldwell,
Sam
Pickard,
and
H.
A.
Lafount.
Not
one
of
these
members
has
a
technical
radio
background
which
would
enable
them
to
better
struggle
with
the
complicated
problems
which
confront
them.
of
international
conferences,
on
whatever
make
rather
dull
reading
for
the
general
public
and
the
Washington
Radio
Conference
has
beer.
11O
exception
to
this
rule.
The
proceedings
may
not
be
exciting,
but
the
results
are
certainly
important.
There
has
been
no
revision
of
international
agreement
since
the
London
conference
of
1912,
and
radio
progress
has
been
so
rapid
since
then
that
the
articles
of
that
Convention
were
hopelessly
inadequate
to
meet
present
needs.
There
have been
many
rocks
and
shoals
in
the
way
of
the
present
conference,
which,
at
this
writing,
has
just
wound
The
Screened
Grid
Tube
208
211
THE
reports
subject,
usually
What
Set
Shall
I
Buy?
-
Edgar
H.
Felix
"Our
Readers
Suggest
213
-
Why
I
Installed
a
Cooley
Picture
Receiver
-
-
-
Edgar
H.
Felix
215
217
219
221
Suppressing
Radio
Interference
A.
T.
Lawton
-
Are
Programs
Going
The
Listeners'
Point
of
in
the
View
Wrong
-
Direction?
John
Wallace
Staff
A
Vacuum'Tube
Voltmeter
Radio
Folk
You
Should
(i.)
The
Laboratory
Drawing
by
Franklyn
-
work,
but
through
good
management
and
a
praiseworthy
general accord,
the
delegates
have
succeeded
in
drawing
up
a
Convention
which
well
meets
the
needs
of
radio
up
its
desire
for
Know
F.
Stratford
225
Ralph
H.
Langley
today.
Not
the
least
important
decision
reached
at
Washington
was
that
dealing
with
the
international
assignment
of
channels
in
the
frequency
spectrum.
In
that
respect,
we
are
glad to
note,
the
future
needs
of
short-wave
communication,
broadcasting,
Some
Fine
Receivers
and
Their
Chassis
"Strays"
from
the
Laboratory
How
Reliable
are
Short
Waves?
Mathematics
of the
Audio
Transformer
-
226
228
High-Powered
Bunk
New
Apparatus
-
.-
The
ama-
commercial,
and
amateur
work
were
provided
for.
a
teurs
had
a
hard
fight,
but
room
has
been
saved
for
them
result
of
which
the
broad-minded
directors
of
the
American
Radio
Relay
League
may
well
be
proud.
Concomitants
of
Good
Quality
230
THE
extremely
.
issue
of
interesting
RADIO
BROADCAST
before
you
contains
some
articles.
The
story
by
Howard
How
As
the
"Synchrophase"
Seven
Was
Developed
John
F.
Rider
232
235
238
the
Broadcaster
Sees
It
Carl
Dreher
"Radio
Broadcast's"
Laboratory
Information
Sheets
No.
No.
No.
No.
153.
Standard'
and
Constant-Frequency
Stations
154.
155.
156.
No.
No.
No.
No,
157.
Table
158.
Wavelength-Freauency
Conversion
Reflex
of
for
Rhodes
on
the
problems
of
push-pull
amplification
is
distinctly
helpful
and
should
cast
much
light
on
a
form
of
amplification
which
is
again
being
revived
after
several
years
of
comparative
disuse.
Those
who
are
anxious
to
know
what
the
new
screened-grid
tube
will
do
will
find
Keith
Henney
's
article
very
valuable
indeed.
As
soon
as
possible,
RADIO
BROADCAST
will
give
its
readers
data
on
receiving
circuits
which
can
be
used
.
.
with
the
tube;
the
The
na-A
and
latter
has
just
Wave
171-*
Type
Tubes
The
Three-Tube
Roberts
Diagram
Reflex
been
released
for
general
sale.
Traps
Wavelength-Frequency
Conversion
159.
Three-tube
Roberts
160.
Fading
-
Manufacturers
Booklets
Available
-
244
246
"Radio
Broadcast's"
Directory
of
Manufactured
Receivers
A
Key
to
Recent
Radio
Articles
What
Kit
Shall
I
E.
G.
Shall<hauser
255
257
Buy?
..>'*,
of
our
readers
who
would
like
to
have
their
names
to
the
manufacturers
of the
special
apparatus
necessary
to
construct
a
Rayfoto
receiver
may
send
letters
to
the
undersigned,
and
printed
matter
containing
detailed
in-
formation
will
be
sent
them.
.
.
The
next
RADIO
BROADCAST
will
contain
an
article
describing
a
new
super-heterodyne,
entirely
operated
from
a. c.,
which
has
much
to
recommend
it,
both
from
the design
and
appearance
point
of
view.
There
will also
be
many
other
articles
of
interest.
WILLIS
KINGSLEY
WING.
THOSE
forwarded
.
Doubleday,
Page
&
Co.
Doubleday,
Page
Gr
Co.
MAGAZINES
COUNTRY
LIFE
WORLD'S
Doubleday,
Page
Sr
Co.
Doublfday,
Page
&
Co.
BOOK
SHOPS
(Hooks
of
.
OFFICES
GARDEN
CITY,
N.
Y.
F.
OFFICERS
N.
DOUBLEDAY.
President
NELSON
DOUBLEDAY,
ue-President
/
GARDEN
&
HOME
BUILDER
RADIO
BROADCAST
SHORT
STORIES
EDUCATIONAL
REVIEW
LE
PETIT
JOURNAL
EL
Eco
FRONTIER
STORIES
'
WORK
all
Publishers)
LORD
&
TAYLOR
BOOK
SHOP
PENNSYLVANIA
TERMINAL
(2
Shops
GRAND
CENTRAL
TERMINAL
38
WALL
ST.
and
526
LEXINGTON
AVE.
5
848
MADISON
AVE.
and
166
WEST
}2NDST.
t
NEW
,
ST.
Louis:
223
N.
I
8TH
ST.
WEST WEEKLY
THE
AMERICAN
SKETCH
KANSAS
CITY:
920
GRAND
CLEVELAND:
In,
MI
Co.
SPRINGFIELD,
MASS.:
MEEKINS.
PACKARD&
WHEAT
and
4914
MARYLAND
AVE.
AVE.
and
206
W.
47TM
ST.
YORK:
285
MADISON
AVENUE
BOSTON:
PARK
SQUARE
BUILDING
CHICAGO:
PEOPLES
GAS
BUILDING
SANTA
BARBARA,
CAL.
LONDON:
WM.
HEINEMANN
LTD.
TORONTO:
OXFORD
UNIVERSITY
PRESS
S.
A.
EVERITT,
Vice-President
Secretary
RUSSELL
DOUBLEDAY,
JOHN
L.
J.
J.
HESSIAN,
Treasurer
LILLIAN
A.
COMSTOCK,
Assl.
Secretary
McNAUGHTON,
Asst.
Treasurer
OOUBLEDAT,
PAGE
&
COMPANY,
192
Garden
&ty,
Company.
All
rights
reserved.
cents.
Copyright,
1927,
in
the
United
States,
Newfoundland,
Great
Britain,
Canada,
and
other
countries
by
Doubleday,
Page
TERMS:
$4.00
a
year;
single
copies 3?
RADIO
BROADCAST
ADVERTISER
193
OUJu
Jlmpli
A
Home
Assembled
Thordarson
Power
Amplifier
Will
Make
Your
Receiver
THORD
ARSON
171
TYPE
POWER
AMPLIFIER
Built
around
the
Thordarson
Power
Compact
R-171,
this
Power
amplifier
supplies
"A,"
"B,"
and
"C"
current
for
one
t/X-
171
power
tube
and
B-voltage
for
the
receiver.
Employs
Raytheon
B.
H.
rectifier.
A
fier.
Real
Musical
Instrument
in
the
^IMPROVEMENTS
JJ
ing
sets
are
all
newer
model
receiv
centered
around
the
audio
ampli'
reason,
however,
why
you
cannot
bring
your
present
receiver
up
to
1928
standards
of
There
is
no
tone
quality
by
building
your
own
Thordarson
Power
iron
fier
Amplifier.
With
a
screw
driver,
a
pair
of
pliers
and
a
soldering
you
can
build
any
Thordarson
Power
Ampli'
in
an
evening's
time
in
your
own
home.
Com'
simple
pictorial
diagrams
are
furnished
with
every
power
transformer.
plete,
i
i
The
THORDARSON
210
TYPE
POWER
AMPLIFIER
This
amplifier,
mounted
on
a
special
metal
chassis,
uses
the
Thordarson
Power
Compact
R-21Q.
Provides
"A,"
"B,"
and
"C"
current
for
one
UX.-21}
power
tube
and
"B"
voltage
for
the
receiver.
Employs
one
216-B
o/
281
rect:fier.
Thordarson
power
trans'
formers
are
used
by
such
leading
manu'
fact
that
facturers
as
Victor,
Brunswick,
Federal,
Philco
and
Willard
insures
you
of
mv
questionable
quality
and
performance.
Give
your
radio
set
a
chance
to
reproduce
music.
Build
a
Thordarson
Power
Amplifier.
real
Write
today
for
complete
constructional
booklets
sent
free
on
request.
THORDARSON
210
PUSH-PULL
POWER
AMPLIFIER
This
heavy
duty
power
amplifier
operates
two
210
power
tubes
in
push-pull
and
has
an
ample
reserve
of
power
for
"B"
supply
for
the
heaviest
drain
receivers.
Built
with
Thordarson
Power
Transformer
T-2098,
and
Double
Choke
Unit
T-2099.
THORDARSON
ELECTRIC
MANUFACTURING
Since
1895
"Transformer
Specialists
CO.
WORLDS
OLDEST
AND
LARGEST
EXCLUSIVE
TRANSFORMER
MAKERS
and
Kingsbury
Streets
Chicago.
1
'II.
USA.

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