Browning 35 Schematic

154

SHORT WAVE CRAFT for JULY, 1935

The . .

"BROWNINC

One of the important features of the Browning 35 "All-Wave" receiver is

. FUNDAMENTALLY,the onlyreal

form is that it should provide a better
set for less money where the builder is

willing to do his own assembling and
wiring. The complete set market is sur-
feited with cheap and medium-priced
sets built on a large production basis
which give fair or indifferent results.
Such receivers are usually worth about
what they cost and are cheaper to buy
than to try to build. But in the more
exclusive field of really high-class radio
receivers the market is far from being
overcrowded. The few sets of this type
which are available are expensive and
beyond the reach of the average radio
fan's pocketbook.

the radio experimenter who wants the
finest results and who is willing to do

some of the work himself to obtain
them economically that the "Browning

35" was developed.

that continuous band-spread is available on all bands.

excuse for a radio receiver in kit

It was to meet the requirements of

Low "Noise-Level" Boosts DX

In designing this receiver we have

had constantly before us certain re-
quirements which must be met:-

In the first place it should be a really

fine modern receiver, which meant an
an.wave superheterodyne incorporat-
ing a stage of efficient radio frequency

amplification on all bands. .

Secondly, it must have a satisfac-
tory quality-selectivity compromise. It
is a simple matter to design an ultra
selective receiver with poor reproduc-
tion characteristics. Or, good repro-
duction is no problem if broad tuning
is allowed. Combining these two re-
quirements in the same set is a differ-
ent .story and requires the utmost care
in circuit design.

Next this receiver must be capable of

not only good long distance reception

but of the very finest distance recep-
tion possible with present tubes and
standard equipment. We have persisted
in this requirement from the begin-
ning, as much of the pleasure and fas-

cination in an all-wave set lies in the
satisfactory reception of foreign sta-
tions. To accomplish this result, (and

35"

- AII-

Wave Receiver

By Clenn H. Browning

The Browning 35 receiver was especially
designed to be readily assembled by the
average short-wave experimenter and it
provides "band-spread" on all bands. The

set covers the complete range from 13.2 to
555 meters.

we feel that we can safely say that it
has been accomplished in the "Brown-
ing 35") one requirement stands out
above all others, namely, a low noise-
level! Adequate sensitivity is of course
necessary but if carried too far this is
often more of a liability than an asset.
What we are after is good signal vol-
ume with the least possible noise.

In general, these are the features

which distinguish the really fine radio
receivers from the mediocre ones. Our

final requirement, which was the most
difficult of all to meet, was that this
receiver should be so designed that it
could be easily assembled by the aver-
age radio experimenter, with the as-
surance that when the job was com-

pleted it would retain all of these de-
sirable characteristics.

This last requirement, which we con-

fess seemed almost insurmountable at
first, was finally accomplished by the
use of a new piece of radio equipment

-the TORE,SUPER-TuNER.

(Continued on page 174)

/

5,000

....

FIELD COIL

1,800

OHMS

-..,-

e"'F.

(EACH)

Wiring diagram for the Browning 35, showing the simple and straightforward arrangement of the various stages, including the

beat oscillator.

OHMS

~SW

1 .-TUNER. CONSISTS OF FOUR-SETS OF COILS

L1,L2.L3,L4.LS,L6 WITH "'TUNING AND

TRI ER CONDENSERS AND CHANGE OYER.
SWITCH !'DR !'DUll. BANDS(MOUNTEOWITHINONECAN)

2:- 0 I'OIIITS WHERE COILSARESWITCHEO(DIA-

GRAMSHOWSONLYONESETOFCOtLS)

3:- RESISTORS ALL '/4 WATT UNLESS

NOTES

OTHERWISE SPECIFIEO

174 SHORT W AVE CRAFT for JULY, 1935

Short-Wave

600

4.. Stations

NEW

Short Wave

Listener

are listed in this magazine!

WEARE happy to present to the thousands of short wave fans this
new magazine which enthusiastic readers of Short Wave Craft have urged
us to publish. Here is a book that you will feel proud to possess because
it reflects your patience and perseverance in logging distant stations. It is
a record you will be proud of in days to come. It is the finest and most
complete book of its kind ever published. There is nothing like it on the
market now, nor was there ever a book published like it before.

It contains the largest listing of short wave stations in the world, a

much larger list in fact than the list published in SHORT WAVE CRAFT,

4600 SHORT WAVE STATIONS

or any other magazine. Due
to space limitations, no regular
magazine can publish all the
world stations. There are so
many short wave stations, which
normally cannot be included in
any monthly magazine list, but
frequently you hear these calls
and then you wish to know
from where they originate. The
OFFICIAL SHORT WAVE
LISTENER gives you this infor-
mation, besides a lot of other in-
formation which you mUOltha-e.

.

"Out of Tunc"

Contents 01 the Jldfllssue:

Talking "Around the World" By Short Waves
Short- Waves Stars of Station PHI, Holland.
Where to Find the Short-Wave Stations on Your Tuning DiL
How to Get Maximum Results from Your SW Set by George
The Latest Style in Doublet Aerials
Why Is a Multi-Tube Set Superior to a 1 or 2 Tube Set?
Short-Wave UFiction" Story
Photos of Short-Wave Artists From India, U.S.S.R., and Other
Silver Cup Trophy Contest for the Best "Listening Post" Ph.
Grand List of Short Wave Stations of the World-With ea.:...Lee

Frequencies. Including "Police" and "Television" Stations

"Star" Short-Wave Station List

Newest Ideas in Short Wave Receivers

"Musical Signatures" and Foreign Language Alphabets-A c.-

Identifying Stations

"The Listener Asks"-Shorb Wave Question Box

From this you will see that th( magazine has been dE"

a companion magazine to SHORT WAVE CRAFT.

If you are now a reader of SHORT WAVE CRAFT
you will not wish to' be without THE OFFICIAL SH~ E'7
LISTENER MAGAZINE. The new magazine will he:;-
mendously in your short wave reception at all tim~

give you priceless and invaluable information, such a",:: _ _' I .

get anywhere else. Nothing like it appears in priD'
today. THE OFFICIAL SHORT WAVE LISTENER ~
in other words, is a necessity.

P. S.-If you cannot get the magazine at your neWSS'c_- [.-
sell-out, send 25c in cash, stamps or money order. ~ .- .-
send the magazine to you direct, prepaid.

OFFICIAL SHORT WAVE LISTENER ~L-\.G;.:-" I

99 Hudson Street, New York, N.Y.

Please mention SHORTWAVECRAF"I' - .:

ASK YOUR

NEWS DEALER

FOR A COpy

OF THIS NEW

SHORT-WAVE

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.

2Sc tile C81'Y

Well

lllustrat~4

.

-

The "Browning 35" -AII-

Wave Receiver

(.continued from page 154)

The Heart of the "35"

This tuner is the "heart" of t!le

"Browning 35" around which the set is
built. It contains in a single unit the 3-

gang variable tuning condenser, with its
vernier control; twelve tuning coils, three
for each of the four separate frequency
ranges, in separate shielded compartments;
a trimming condenser for each one of these
twelve coils, together with the variable and
fixed padding and tracking condensers.

The SUPER TUNERalso contains a silver-

plated, multiple band, selector switch which
passes through the shielded compartments
with a coil-switching unit in each com-
partment. By means of the unique wiring

arrangement of this switch the coils not
in use are isolated and short-circuited. The

individual parts of the unit are carefully
arranged and spaced from the shielding
walls to keep inductive losses and stray
capacities at a minimum. Not only is the
SUPER-TuNER completely assembled and
wired at the factory, but the circuits and
trimming condensers are also alined and
preadjusted; the R.F. detector and oscil-
:a.or circuits are all synchronized and ready
", operate. Thus the complicated and crit-
~ part of the electrical and mechanical

a;.asauetion is eliminated and the remain-

=:; 6S:5embl~' and wiring work on the

~,;s can be done by anyone familiar

-.~~ ;;;.e use of soldering iron, pliers, and

-.;- ..;:ri-er.
rlliqae Construction Plans

E-~ !' ed ;he problem of how the

'20- = oIL_ ..onstruct such an advanced

__ ' "..;- utilizing the SUPER-TuNER,

_- .".- - torn was that the remaining

... - .-_ -'..ring work should be made

_- _- .' proof as possible. Accord-

__ -~ 2Ie drawings are furnished

ine first shows a large

-0

~ M .f the circuit. Drawing

_- ;Q assemble the parts.

- ~wl all wiring on the

-~ tJae filament and power

~nsitivity and volume

He. Diagram No. 4

. of every fixed resistor

Diagram No.5 shows

<" ,nnect each fixed con-

-..;ng, except the sev-

1:. are made last of all

-

_<. these diagrams are

parts (sockets, power

-e resistor controls,

:Or5t mounted as shown

Then the general wir-

- n. to point exactly as

- 3. The small fixed

- toected to the sockets
...rovided for them in

mm No.4. Then the

- ~ted as in Diagram
SUPER-TuNER con-

7 _c tuning unit should

':1::til all wiring and

,n completed. This

- ,rk on the chassis

- ing the tuning unit

~ -ith a reasonable

el""e its adjustment.

_::.c.s Preselector

-" circuit used in the

eral unique and ad-

- _ eh are-in large
be exceptionally fine

.~ on long distance

-

!>..ageof tuned R.F.

~;jon, as it is some-

used ahead of the

bands really am-

=-the circuit is not

_ :. will prove more

- _«set on the high

~ the sensitivity in-

-

Silver-plated wire

""IUency tuning coils

~r circuits, and

SHORT WAVE CRAFT for JULY, 1935

every precaution is taken to eliminate

resonant circuit losses ahead of the mixer
tube. It is this part of the circuit which
must be depended on to eliminate "image"
and "pseudo image" frequencies wl1ich are
so annoying, even in many of the higher-
priced receivers. Moreover, if a reason-
ably high order of amplification can be
obtained in this preamplifier, and this is

View of Tobe Tuner

entirely practicable with the help of a 58

supercontrol tube and low-loss circuits,
it permits the use of less intermediate

frequency amplification which helps tre-
mendously in reducing the noise-level of

the entire receiver.
Tuning Range from 13.2 to 555 Meters

The "Browning 35" covers the whole
short and long wave broadcast tuning
range up to 555 meters, or the entire

frequency spectrum between 22.6 and .54
megacycles. Its sensitivity throughout
this wide range is better than one micro-
volt which means that the R.F. gain is
greater than can be used except under the
most favorable atmospheric conditions in
a very "quiet" receiving location. It can
be seen from the accompanying sensitivity

curves that the response on anyone band

is almost uniform while the entire vari-

ation over all four bands is unusually small.

The uniformity of these curves is a direct
indication of the high efficiency of the all-
wave tuning unit employed.

The receiver is absolutely single-control.
The twelve trimming condensers and four

tracking or padding condensers in the

SUPER-TuNERunit make it possible to main-

tain accurate synchronism between the pre-

selector, detector and oscillator circuits
over the entire frequency range.

Band-Spread Over Entire Range

Tuning is done with a 40 to 1 ratio
microvernier dial. Stations are logged by

reference to two pointers, one on the main
shaft of the tuning condenser and the
other on the vernier shaft. The vernier
dial has a 2'1.," diameter and covers 3600.
Thus continuous band-spread is accomp-

lished over the entire tuning range. The
advantage of such tuning control can be
seen by considering one individual band.
Take, for instance, the highest frequency
band which tunes from 22.6 megacycles

(13.2 meters) to 8.8 megacycles (34 me-
ters). On the large calibrated dial this
band is 8'1.," long. While the long point-
er on the main dial is covering this dist-
ance the vernier pointer makes 20 com-
plete revolutions on its 2'1.," scale, covering

actually 15%.". The 20-meter amateur

phone band, which is only 100 kilocycles
wide, covers 720 on the 2%" vernier dial!

Oscillator Is Electron-Coupled

The beat frequency oscillator is combined
with the first detector and electronically
coupled to it in the 2A 7 tube. This pre-
cludes any "locking-in" effects between the
antenna or R.F. stage and the oscillator.
Another feature of the oscillator circuit is
the parallel voltage feed to the anode.
This can be seen by reference to the
accompanying schematic circuit diagram,
where the 20,OOO-ohm resistor is shown in
series with the power supply and in parallel
with the plate inductance of the oscillator.
This circuit arrangement tends to keep the
R.F. output of the oscillator at a con-
stant level over its tuning range and per-
mits more efficient operation of the mixer.

Double Band-Pass Filter

Only one stage of intermediate frequency
amplification is used. This was done delib-
erately in preference to using two or more
stages, and not for the sake of economy.
The 58 super control tube, which is used
here, has an amplification factor of 1280
and, when used with effective high im-
pedance grid and plate coupling, is cap-
able of delivering as much intermediate
R.F. amplification as can be used under
actual operating conditions.

It is common practice to make use of
two or more intermediate stages of am-
plification operating at low efficiency, each
slightly off resonance with the other, in
order to obtain a selectivity and ampli-
fication curve which is not too sharply
peaked. While this is good theory, from

a practical standpoint the results are not
always satisfactory. Tube capacities vary,
their characteristics change and tuned cir-
cuits shift their peaks. An oscillator, to-
gether with an oscillograph, are necessary
to properly readjust such an I.F. amplifier.

The "Browning 35" makes use of a

double band-pass filter to accomplish this

purpose. Six tuned circuits are employed

in this one I.F, stage, two of these being
link circuits which are conductively con-
nected only to ground, and are consequently
not affected by tube variations, etc. Three
of these filter circuits are contained in

each of the two I.F. transformers, the
center one in each case being the inde-
pendent link circuit. It is a simple mat-
ter to align these circuits at any time
by merely adjusting the two outside cir-
cuit condensers in each transformer so
that their circuits are in resonance with

175

FREE

TO WINNERS OF
SWST with BB's-

A WHOLE YEAR'S SUPPLY

OF BURGESS

BATTERIESt

Wire new BB's (BURGESS Batteries)
to your set. They'll give it the full
power, the razor-edge seleCtivity, the
heightened sensitivity you need to
win the SWST (Short Wave Scout
Trophy).
number of stations. Mail your record

to Short Wave Craft. WIN the SWST

-and get a year's supply of BB's (all
your set can use in a year!) absolutely
FREE.
FREE, if your prize-winning set is
powered by BB's! Visit your nearest
dealer and get those new BB's-and
pick a prominent spot for your SWST.
BURGESS BATTERY CO., Freeport, Ill.

.Tune in a prize-winning

.A year's supply of BB's

1.0

U')

;::--.

>-

.8

1-0

->
o

.6

!::d

If)W

z-

;4-

wZ
<f)

.2

BAND4-.55 .65
BAND 3-1.42 1.70
BAND 2- 3.4

BAND 1-8.5

"--

......10.:.:

BAND 3../

4.03 4.66 5.29

10.1

BAND 1 "'\

-

....,...

..........

BAND 2

.75
198

11.7 13.3 14.9

FREQUENCY IN MAGACYCLES

Sensitivity Curve for "Browning 35" Receiver

l

BAND 4 "-

I

I I

.85 95

2.26

2.54

5.92 6.55

Please mention SHORTWAVECRAFTwhen writing advertisers

1.05 1.15

2.82

16.5

.

3.10

7.18 7.81

18.1

1.25 1.35

3.38

3.66 3.94

8.44 .9.17

19.7

21.3

1.45

22.9

BURGESS

Power

House

BURGESS "B" and

"C" Batteries

BURGESS

BATTERIESAND FLASHLIGHTS

j
I

I

176

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A high Impedance
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an appreci-

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curreot.

.

Brush Type A
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short wave ama..
teur and experi-
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their sensitivity.
They can also be
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.

The driving mech..
anism of Brush
Type A piezo-
electric h EIa d
phones is assembled in a disUnctive brown octagonal bake-
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and very l1~ht in weight-the entire assembly. including
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They have a response from 60 to 10.000 c;rcles, whirh wide
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The high impedance and great sensitivity enable the phones
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Jt you wish to learn of its many uses,
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IMMEDIATE DELIVERY

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.
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-..

SHORT WAVE CRAFT for JULY, 1935

the link circuit. This is done by listening
to the noise level in the loudspeaker and
simply adjusting the top and bottom tun-
ing condensers in the transformers for
loudest volume.

After much experimenting 456 kc. was
chosen as the best intermediate frequency
for the band-pass filter and the six cir-
cuits are preadjusted for this frequency
at the factory. This adjustment is made
on R.C.A. tubes, but regardless of tube
variations the link circuits remain on 456

kc. and it is a simple matter to bring th~
others into resonance as described abo\"e.

Further advantages gained by the use
of this band-pass I.F. filter in selectivity
and quality of reproduction will be given
next month together with a description
of the remainder of the circuit which in-
cludes linear diode rectification in the final
detector, automatic and manual volume con-
trol, sensitivity control, a beat frequency
oscillator and resistance-coupled audio
amplification.

Beginner's All-Electric S-W Receiver

(Continued from page 141)

supply is used with other sets. However,
for this set no taps were needed and the
straight 15,000-ohm, 35-watt resistor was
used. If a dynamic speaker is used the
field coil can take the place of the second
filter choke and should have a value of
1800 to 2000 ohms.

The chassis used for both the power sup-
ply and the R.F. and audio section are of
aluminum and measure 4 x 9 x 1'h inches,

6 pin base for use with .00014 mf. (140 mmf.) tuning conde"ser

Primary. Secondary

Band W.L.

10-20 meters

20-40

40-80

80-200

"Tickler coil wound at bottom or pin end of 1'14" dia. form.
Prim. Turns interwound at lower end of Sec. (nearest tickler).

This winding not used on Uantenna" coil.

4T. No. 32 S.S.C. In- 5T. No. 26 S.S.C. Tickler Dis. bet.
terwound with sec.
turns

8T. No. 32 S.S.C. In-
terwound
turns.

15T.

No.
Interwound with sec. wound
turns. bet. turns.

31T. No.
Interwound with sec.
turns.

"S"-WINDING COIL DATA

(tickler end.)

sec. wound

with
32

S.S.C. 23T. No. 26 S.S.C. 8T No. 30

32 S.S.C.

making a really compact receiver. The
photographs clearly show the placement of
the various parts. We recommend that the
very same layout be used, if best results
are to be expected. The antenna used dur-
ing the tests performed with this receiver
was 75 feet long and gave fine results.
Nearly every foreign SoW broadcast station
was heard on the loudspeaker-and with

very comfortable volume.

wound -h" pitch bet.
turns. S.S.C.

liT. No.
bet. turns.

50T. No.
wound
bet. turns.

3/32"

5/64"

1/32"

26

S.S.C.

30

S.S.C.

5T. No. 32 Tick. & Sec.
7T. No. 32

16T.

S.S.C.

S.S.C.

No.

S.S.C.

pitch

pitch

pitch

30

3/32"
3/16"

3/32"

5/32"

SuPER-SKYRIDER" (is- to.240)Complete $59.95
SUPER-SKYRlDER (13 to 240) with Cryst.l,

Complete 68.95
SUPER-SKYRIDER (13 to 550) Complete 69.95
SUPER-SKYRIDER (13 to 550) with Cryst.l.

Complete 78.95
SUPER-SKYRIDER (10 to 240) Complet 69.95
SliPER.SKYRIDER (10 to 240) with Crystal.

Complete 78.95

SARGENT 8-34 (15 to 550) Complete 54.50
MARIXE )IODEL 8-34 (15 to 1500) Complete 62.50
PATTERSON PR-12 (8 to 550) Complete 83.70

\\"ith cn':;tal. ('OIDP)ete..mu_m..m m_m_ 89.70
R)IE-9D (13 to 550) 112.50

Complete with tubes, speaker. speaker cabinet,

etc. 127.50
RCA.AC'R 136 (15 to 550) Complete 69.50
)Ic)IURDO-SILVER 5C (13 to 200) Complete 74.70

RARGEJ'.'T. complete 14.75

r.£R~~e~?~ube~~~.~~.~~::::::::::::::::::::::::::::::::::::::: I~:t

SHIPPEDPREPAID~~cof~~.nf~:c~~t~::j~~

PRE-SELECTORS

. CR:\!E-9D aDd RCA-ACR-136 u('~pted)

MARINE RADIO

COM PAN Y

(Formerly L. I. Marine & Electric Co.)

124.07 10Ist Ave., Richmond Hill. New York City

Tel. Cleveland 3-2400. Cable Address "Elecmarine.'

. .

.

This bottom view
shows the place-
ment of parts.

Note that the
panel is spaced

from the chassis
to accommodate
the antenna
trimmer and re-
generation con-

trol.

.

. .

ARTICLES ON GOOD 1 TO 5 TUBE SETS WANTED!

The Editors are looking for good set construction axticIes on:
A-One and Two Tube Receivers.
B--Sets using new "dual-purpose" tubes.

C--S- W Converters of efficient type and proven worth.
D-Transmitters, low-power, efficient types, and allied "Ham" station

apparatus including Monitors, etc.

Send diagrams of set first and photo for editor's opinion, before ship-

ping set.

Please mention SHORT W AVE CRAFT when writing advertisers