The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1925-12-18
BY GEORGE M. MEYER,
IN the New York Herald Tribune.

VI
BY GEORGE M. MEYER,
In the New York Herald-Tribune.
How would you like to build four
tube set that would give volume al
most equal to any five-tube receiver
on the market? 1t can be done. The
receiver about to be described may be
constructed without the use Of 'low-
loss parts or trick-wound coils. 1t is
an excellent receiver and as for vol
ume and clarity Of reception, nothing
more could be desired.
The circuit makes use of a stage OF
radio-frequency amplification which
seems to supply tremendous volume to
the detector tube.
1t is the writer's opinion that
greater radio-frequency application
per stage can be obtained when the
circuit Is tuned In single circuit fash
lon; that is, with a condenser con-
nected in series with the antenna tun-
Ing coil rather than across a coil hav-
Ing an untuned primary winding. In
past experience with receivers en-
ploying a stage of tuned radio-fre-
quency ahead of the detector results
have shown that greater application
OF radio-frequency currents is possible
with the series circuit. In fact this
type of circuit has been known to
produce as much application as two
stages of tuned radio-frequency en-
ploying condensers shunted across sec
ondary coils and nontuned primaries.
1t is for this reason that this four-tube
set will produce as much volume and
receive as much DIX as some five-tube
tuned radio-frequency receivers.
Special couplers or coils are not nee
essary, as the two coils in this re-
ceiver may be homemade. Below is a
list of the parts required to complete
the set:
TIE Parts Needed.
One panel
Two .0O05 variable condensers.
One .00025 grid condenser with
mounting.
One four megohm leak.
One .O02 fixed condenser.
One tube 3 inches in diameter, A
inches long.
One tube inches in diameter. AZ
inches long.
One pair Of audfo transformers.
Seven binding posts.
Four sockets.
Two single jacks.
Two 20 ohm rheostats.
One 10 ohm rheostat.
Two 4-inch dials.
A careful selection of the parts is
essential
Designers of some of the highest
class receiving sets have specified
flexible stranded copper wire for all
filament and plate battery connections.
These leads are all punched together
and tied to keep them out of the radio
frequency circuit. The wires running
to the sockets, binding posts and
rheostats should be kept near the
Dashboard of the set. A receiver
wired in this fashion will not be SUBJ
ject to squeals or high-pitched notes
common to a great many homemade
sets in which the "a" and "B" battery
circuit is allowed to traverse the tun-
ing circuit.
Secondary Tuning Coil.
The secondary tuning coil which
feeds the detector tube should be
carefully made and wound tightly
with No. "a d. G. c. or d. S. c. cop
per magnet wire. There are three sep
arate windings on this coil, one for the
plate of the radio-frequency tube, the
secondary and the plate coil of the de-
tector circuit. The tube should be
three inches in diameter and four and
one-half inches long. Start about half
an inch from one end and wind nine
turns of wire, being careful to pre-
vent the wire from coming unwound.
Fasten each end of this small winding
through small holes in the tubing.
Then in the reverse direction wind
the secondary coil with 40 turns of
wire. Leave one-Quarter of an inch
between the first winding and the Sec
ondary. Remember the secondary coil
is wound directly opposite to the nine
turn coil. Both ends of the secondary
winding should be fastened through
holes In the tubing. Skip half inch
and wind nine more turns of wire in
the same direction as the 43-turn wind
ing. You now have completed the
coil. 1t may be mounted in back of the
secondary tuning condenser and