The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1926-01-08
BY SIDNEY E. FINKELsTEIN.
In New York HeraId.T ribIna

In New York Herald Tribune.
The honors In audio-frequency am
plification seem to be divided more or
less evenly between the transformer
and the resistance coupling methods.
Each system has Its stanch adherents,
VINO are ever ready to fling masses of
facts, figures and fancies into each
others faces whenever a discussion
or relative merits arises. The trans
former supporters are just as firm In
their belief of the superiority Of their
Instruments as the resistance bench
men are In their views on the advan-
tages of their devices.
The writer has used both transform
ers and resistances in the construc-
ton Of large number of sets, and
after studying the general results OBJ
tanned from them has come to the
neutral conclusion that both systems
are good, but that they are even bet
ter II they are combined, In the jour-
nalistfc fashion, to the retainment Of
the best features of each.
The advantage Of the greater am
plification per stage afforded by the
transformer, combined with the flaw
less reproduction but lower amplifca-
ton OF the resstances, makes the
ideal combination In the majority of
sets.
complete amplifier of this ad-
vantageous type can be made at home
at surprisingly little trouble and ex-
pense, and once on hand it finds ap-
plication to receiving circuits of all
kinds. 1t may be built permanently
into set or 1t can be left available
as a separate unit for connection to
experimental tuners. For the last
purpose 1t Is especially convenient,
as 1t saves the constructor of a new
set the worry of providing suitable
application to follow the detector
tube.
Parts Required
An amplifier such as the one shown
In the illustration will require the
following parts, which can be pur-
chased at any radio store: Hard rub
Der or composition Dashboard II inches
long, AZ inches wide and u inch
thick; one heavy audio transformer
not above 314 to / ratio, three stand
ard tube sockets, two resistance cou-
pling units with two 100000, one $780,
600 and one 100000 ohm resistors; one
.0005 mid. fixed condenser, eight bind
ing posts and the usual busbar and
mounting screws
A definite assembly procedure
should be followed First the general
location of the instruments should
be determined and all the necessary
screw holes made in the panel before
anything is fastened down perma-
Dently.
The devices should be pushed
closely together (there is no danger
from interstage bowling. as there is
only one transformer, so as to allow
room on the right and left hand short
edges for input and output binding
posts.
E The wiring will give no trouble.
As a start the "P" and "B'' posts of
the simplifying transformer should
be connected directly to the two bind
ing posts on the extreme left, which
are designated as the ''input" ter
minals The ..0O05 mid. fixed con-
denser is also placed across the wires
and can be hidden comfortably out
of way beneath the bottom of the
Dashboard. OF course small holes
will have to be drilled In the COM
position to pass the wires wherever
necessary.
The FlIament Posts.
Next the filament posts of the three
sockets. which are all marked "F,"
are wired as shown In the diagram.
and lead finally to the A battery
binding posts. These should be the
left hand two of the row of four
along the long edge of the Dashboard.
With this much done the secondary
of the transformer can now be wired
to the grid and filament posts of the |
first tube socket. Progressing across
the condenser and resistor terminals
are wired in the manner indicated in
the accompanying hook-up. With the
resistor units that were employed in
this particular amplifier the protrud-
ing soldered tabs of the spring mount
ings make the placement Of the wires |
short and simple task.
The two posts on the extreme right |
are the output. To one is run a wire
from the P terminal of the last |