Evening star., 1924-07-27
Tuner Is Adaptable to
Modification of
Navy Types
GOOD FOR DISTANCE
Constructor Points Out
Achievements With
One Tube.
BY f. l.. CECIL.

BY r. L.. SfSlI.
A number of articles have been writ
ten condemning the single circuit re-
generatiye tuner, but, after all, the
! fact remains that it is one of the best
distance and volume setters of any
circuit yet developed. with the pos
sibie exception of the reflex. 1t Is
| also adaptable to many notifications
and may be constructed at minimum
! cost.
The set described in this article is
Imodification of the single circuit and
was designed and constructed by the
writer. The circuit diagram. however.
was taken from one of the leading
! radio magazines. The results obtain
ed were highly satisfactory.
The principal features Of the set
which should commend it to any one
wishing a small, compact receiver for
| outings or home use, are:
If is essentially non-reradiating and
NAV be tuned by the beat note meth
cd with but slight chance OF lnterfef-
ing with your neigh bor. especially ii
a short antenna is used. II is entire-
| " self-contained in a small cablnet
weighing only 6a4 pounds. complete
with all accessories, and may be USED
on most any kind Of antenna. Some
of the objects that have been used
successfully for an antenna are an
automobile. short ciothesilne: ram
spout, bed springs, il short piece OF
wire about Is feet long thrown on
the floor or ground and in the inn
mediate vicinity of the local stations
without either antenna or ground.
Cuts Out Local Stations.
The set is capable of cutting out the
local stations and bringing in sta
tions up to 500 miles in summer, and
a great deal more in winter, on reg
ular antenna:
4 close study of the views of the
set will give good idea of how the
different wires and equipment are
placed.
The inside dimensions of the cabi-
net are 5Ss inches wide, Obs inches deep
and inches high.
The outside dimensions will depend
on the thickness of the wood used in
its construction. The writer used Il
inch thick 3-ply panel material and
covered it with leather. However, the
finish may be left to the lndlVlduais
.own taste.
The list of parts required for the
set are as follows: tThe writer would
caution you to strictly adhere to all
parts and specifications, or you Will
be unable to get the set IN the space
one by 10 radon panel. one
United States tool II plate condenser,
one 2-inch dial, one Pacent socket
for 1sS tube, one .00025 Dubiler grid
condenser, one Daven grid leak y
magohn, two 4-inch spider web
forms, two small inductance switch
arms. l Is radius: two switch points.
two switch stops, one 2o-ohm cutler
hammer resistance. four phone tip
jacks. Two phone tips; one binding
post composition nut. one-quarter No
% double silk covered wire, one-quar-
ter No % double silk covered wire
4-foot bus wire, 15-foot single strang
lamp cord, feet of very flexible COW
cred wire, Is inches fiat brass 1-16
by u inch, 3 inches 3-16-inch round
brass 2 inches !. Inch round brass.
one pair phones, one 299 Cunning
ham tube, one Burgess battery,
smallest size. No. 4156; one Burgess
c battery. No. 2370, for A battery;
one dozen soldering Jugs, one piece
hard rubber tubing 3 inch outside,
u inch inside, inches long; one cab
met and base board, miscellaneous as
sortment of wood screws, 4-40 and
6-32 machine screws and nuts.
Take one of the spider-web forms,
Then wind so turns of the No. %
wire on it. with one tap at 40 turns.
This is the main inductance.
Lay out the other spider-web~ coil
to fig. and drill wind SO turns of
the No. % wire on it. This is the
| wound in the same direction and
i when finished should be given a coat
| ing of hot parafin wax to prevent
them from collecting moisture.
.., Circular Shaped Panel
Next cut a piece of the by 10
panel out in a circular shape and
drill according to fig. for the in
ductance and condenser. mount the
! groove shown in fig. 3B will have
| to be bored out on a lathe. Fifteen
turns of the No. % wire are placed
| in this groove and held in by strips
| Of adhesive tape fastened on the face
placed in any particular order. This
! is the primary winding, the begin
| ming of which should be connected
to the aerial and the end to the ground.
| same direction as the other coils. Now
4 lay this aside and cut the piece of
| hard rubber tubing off i q inches
| long and force it on the condenser
shaft. Then take the piece of u Inch
round brass and force it into the
other end of the hard rubber tube
Be, sure that this piece OF brass does
not touch the condenser shaft.
| This arrangement answers a twofold
purpose: First, it furnishes an extension
for the condenser shaft so that it will
reach through the panel, and. second
and most important. it assists in elm
mating body capacity effects.
Take the piece of fiat lie by " brass
| bend and drill three brackets accordine
to figure 4. One of these brackets, which
we shall call bracket F, has hole
drilled in it with No IS drill "A inch
| from one end and in the center Of the
half in dimension. This hole is mounted
nearest the main panel. Now faster
these three brackets to the circular con.
| denser mount with No. 40 counter
| sunk head screws and nuts through
| holes DEF. then fasten the panel te
the condenser with countcr-sunk head
screws and nuts through holes A b
Holes will have to be drilled In the front
of the condenser to correspond to thes<
/ holsss4
The main inductance In now fastened
60 the circular panel directly over the
| primary winding with No. $40 counter.
sunk head screws through the holes IN
th. center Of the spider-web form and
holes - N IN the panel The two ends
| and the center tap are brought out
through hals~ i-2-3 In tho panel tn the
aide the aondcsner " on. Now cut oui
and arm = piece of tho panel to COO
form with hsurs ,. The holes 7 and ]