The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1925-12-18

r. r. application


placed at right angles to the antenna
COIL
If the antenna coil is mounted up
right from the base the coil with the
three windings should be mounted
parallel to the Dashboard. The two
coils should be half-inch apart. The
brackets or by means of small blocks
of wood fastened to the Dashboard.
The secondary Of this coil Is shunt-
ed by 0005 variable condenser The
reversed winding is in the plate circuit
of the radio-frequency tube. The end
nearest the secondary connects to the
"B" battery of the detector tube The
outer end connects to the plate ter
minal Of the radio-frequency amplifier
tube. After the set has been tested, 1t
may be well to try reversing these
connections.
The nine-turn winding which follows
the direction Of the secondary is con-
nected in the plate circuit of the de-
tector tube. When the circuit is
under test, If it regenerates or squeals.
this coil Is wound too near the Sec
ondary. Slide this coil away from the
secondary another quarter inch. This
will prevent the regeneration to the
extent of stopping oscillation. There
will still be certain percentage or
regeneration present which is neces-
In ArIn hot hn rannfunr ffJnP-
ton on distant stations. However, the
set should not sQueal on any wave
length. 1t will not radiate, due to
the blocking effect of the stage OF
tuned radio frequency.
&c" Battery Is Included.
&c" battery seems to be in style,
and so one has been included in the
circuit. 1t will improve reception as
we'll as prevent excessive drain on the
plate batteries. Ninety volts "B' bat
terry will require a &c" battery of 40
volts If one Of the new RCA power
tubes is used In the last stage a great
increase in volume over the 201A will
be obtained.
A word or two of explanation con-
corning the tuning of this receiver is
given to enable those who have con-
structed similar outfits to obtain the
best of results. There are but two
controls as far as actual tuning is
concerned One of these to the left
of the panel is employed TO tune the
first stage Of radio-frequency and the
antenna circuit. The second tuning
condenser is used to tune the detector
circuit. This adjustment is in control
of the wave lengths and may be called
the station selector," as 1t is used to
pick out the stations. If the set has
been properly constructed, this tuning
dial should be fairly sharp on all sta
tions. 1t may be logged.
The radio frequency coil Is wound
on a 3-inch tube about inches long.
No. "a double cotton or silk-covered
wire is required for the winding. The
entire coil contains 80 turns of wire,
with taps take-off at intervals. Start
the winding about half an inch from
the end of the tube, and before taking
the first tap, wind so turns of wire.
Make loop or twist which may be
cleaned later for connections. Contin-
ne winding the coil in the same direc-
ton until the SEVENTEEN turn. Take
another twist and proceed to the
eightieth, where another tap Is taken.
Finish the coil at the ninetieth turn
and leave a short end for connecting
the bus bar wire.
screwed to the bottom of the coil for
holding it in an upright position on
the Dashboard.
This coil should be placed directly
in back of the aerial tuning condenser
and about an inch away. The .0005
variable condenser which tunes this
coil is connected to the top turn. This
should be made to the fixed or sta
tionary plates Of the condenser, In or
der TO avoid any possible "body ca
pacity" The rotor plate connection
goes to the antenna binding post on
strip at the rear of the Dashboard.
The top of the coil also connects
to the grid terminal on the radio-fre-
uuency tube socket. Make the lead
as short as possible and direct to the
socket, avoiding bends and fancy
shaped wires.
The antenna series condenser aids
in bringing about resonance between
the primary radio-frequency circuit
and the detector circuit.