The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1925-10-16
BY SIDNEY e. FINKELsTEIN,
In Radio World.

In Radio World.
For the fan who has made many
sets some variations on the accepted
themes are very inviting, hence two
circuits are presented that offer en-
couragernent to those who like to work
out solutions from suggested data.
The. first circuit Gig. u consists of
a stage Of tuned radio-freQuency am
plification, with its two tubes connect
ed in parallel, regenerative detector,
the first stage Of audio ref1exed in the
parallel-connected tubes, the second
stage of audio being "solo."
The other circuit Gig p, using the
same principle, makes the last audio
stage the refiexed one The parallel
connection of the tubes in the refexed
stage is retained.
Only one reason for connecting tubes
In parallel may be advanced-to make
them share equally the load Of the
stage In which they are connected.
With RI application so popular
often there Is too much of it, so that
distortion arises from RF causes, no
less than from an overburden Of audio
current.
Two Audio Stages Employed.
AS the test is one for reducing the
overload, If any, two audio stages must
be employed. Some may find that the
hook-ups as suggested will improve the
quality of reception. At least expert
mentors may establish to their own
satisfaction which of the two methods,
If either, gives them better results In
quality, and possibly even greater vol
ume than obtained heretofore, when
the four tubes were hooked up simply
in straight fashion.
Constructors who have test boards
will find the circuits very interesting
subjects of experiment. The change
involved In making one into the other
Is slight.
The set, In point of distance getting,
will not accomplish any more than the
regulation hook-up. But If fan is
troubled with distorted reception, In
stead of introducing resistances across
cut down the volume, he may try
either or both of the methods outlined,
and see if he cannot get very clear re-
ception without any reduction in
volume
L1L2 is a radio-frequency transform
er and CT is a variable condenser of
correct capacity to tune the secondary
L2 throughout the band of broadcast
ing. L3L4L5 is 3-circuit tuning coil
in which L5 is the ticker. CO tunes
La CO is a bypass condenser, about
O01 MID. So is C5. R4 is a grid leak,
about 2 megohms.
The tubes are numbered 1, 2, 8 and
4. In effect tubes 1 and represent
only one stage in either diagram. The
input is to the two grids and the out
put is from the two plates. These two
tubes should be of the same type.
Two Tubes In Parallel.
The RF load on the tube is partly
determined by the number of turns on
the primary L3. Generally speaking,
the lesser the inductance and coupling,
the lesser the tendency to overload.
But unless one has ratio of at 4-to-1
there may be losses, /. e., insufflciency
transfer of energy. Assuming, there
fore, one has the type of windings
most commonly used, where that ratio
is used, or something near it, there
may be still quite tendency to ask
too much RF work of the first tube.
Hence we will use two tubes in parallel
for accomplishing only the same guam
titative results. Now, not to require
the use of any more tubes than would
the standard hook-up, we must resort
to refexing. That often causes diff
culties and if the refexing isn't
careful wiring job, with proper regard
for position and length of leads, all at
tempts to attain improved results are