The Washington times., 1923-04-08
FLENELL|NG CIRCUIT
RECEIVER DESCRIBED
Non Technical Explanation OF
Device Assembled by
s Radiophone.
OTlLlZES SHORT AERIALS
Two Applying Tubes Re-
CURED to Give Salts
factory Results.
OTILIzEs SHORT AERIALS
(see Photo Diagram0

fube receivers since the initial an
houncement of the circuit in the
Radio Digest.
The photo diagram is made from
such a set. 1t clearly shows eacn
Individual part used and It's reiaIlNe
position and function.
The purpose of this article ana
diagram is to bring out ana mus
frate in a non-technical manner the
essentials and construction or this
new FIewelIing single tube circuit
for radiophone reception.
DETECTOR UNIT.
Instead Of the vertical panel, as
previously described in these articles,
this set is mounted on long, mar
row nanel. The double honeycomb
coil mounting is located on the left
side.
The dial of the variable condenser
Or the adjustment of the wave
kngth of the grid circuit is located
~, approximately the center OF the
manel. Since 1t is anticipated that
only short aerials will be utilized.
the antenna series condenser has
been omitted, thus reducing the cost
somewhat.
The rheostat control has been
placed in the lower right corner
front view, while Immediately
above it seven holes are drilled for
observation of tube lighting. Five
binding posts are fastened to the
right side of the panel.
= The uppermost of these is for the
antenna or ground connection, de-
pending on which is used, since both
are unnecessary. The second post
is for one phone terminal, and the
third is for the other phone ter
minal. and in addition, is connected
TO the positive side of the approx
n1ately 100-volt B or plate battery.
If the audio amplifier is used, the
phones are removed and the second
and third terminals are strapped
across to the input terminals of the
aInplifier unit as shown in the illus
tration. The negative terminal of
the plate battery and the positive
terminal of the A battery are both
connected to the fourth binding
post from the top: The last or bot
tom binding post is for the negative
terminal of the filament storage
battery.
LEAKS AND CONDENSER BANK.
It will be noted that the leaks and
condenser bank are mounted in the
rear of the panel. Looking at the
rear view, the leak indicated between
the socket and the variable con-
denser is the one usually located in
the grid circuit.
This is the leak that requires the
most careful adjustment. The re-
sistance OF this leak should be very
high In fact, several experiment.
ers with this circuit have been able
to eliminate it entirely.
The other leak and condenser bank
are shown on the right side of the
rear view. This leak is not as
critical in adjustment as the grid
leak. The condenser bank leak SIM
ply requires a few heavy black pen
ell lines. sufficient to keep the re-
sistance- down to at least s. megohm.
TO be drawn between two terminals.
AMPLIFIER UNIT.
The amplifier presents but little
variation from standard construc-
ton. The dial is for filament con-
troll. The two binding posts on the
left are the input terminals and are
connected to the phone posts of the
first unit, as explained before. The
two posts on the right side of the
panel are for the phone connections.
Four binding posts on the base of
the panel are for the A and B bat
terry connections. From left to right,
the first one is for the positive ter
minal OF the A battery, the second
one. the negative terminal of the A
battery. the third one, the negative
terminal OF the plate battery, and
the fourth one, the positive terminal
OF the plate or B battery. 1t should
be noticed that a separate 3 battery
Of 100 volts is indicated for this unit
II another stage of application
were added, this same amplifier
plate battery could be used, but the
detector circuit battery should not
be utilized for the simplifying plate
circuits.
In looking over both the front and
rear views, ii will be noted that the
variable leak resistance used across
the primary of the first audio fire.
quency transformer, as mentioned in
previous articles, is not indicated.
The use Of a separate piece of ap-
paratus has been eliminated and the
grid leak effect is accomplished by
the addition of slight pencil marks
between the two input binding posts
on the face of the amplifier panel.
TUNING OPERATIONS.
In tuning, it will be found that
the coupling between coils and the
setting of the variable condenser is
not as critical as the proper adjust
ment of the high resistance grid
leak. The low resistance leak con
nected to the condenser bank Is first
adjusted to a very low resistance
value.
The coupling of the honeycomt
coils is set at about a 45-degres
angle. The variable condenser dia
can then be rotated for reception
which can be temporarily adjusted
TO about the phone wave lengths
The grid leak should then be ad
5usted for the elimination of nearl.
all whistle and noise, after which
the coil coupling, the rheostat AM
condenser dial can be readjusted.
When the ampIifier is used, tn
resistance between the two inpu
terminals is first adjusted for hes
results, after which the grid leal
must be readjusted.
In working with this circuit tn
experimental must realize that tw
simplifying tubes are required, a
soft detector tubes have not beel
found to give as satisfactory receE