Evening public ledger. [volume] (Philadelphia [Pa.]) 1914-1942, 1922-06-02
The Two.Slide Tuner Is Easy to Build

In the old days Of wireless. before we
suspected that the sound of the human
voice could SO easily be sent and re.
| ceived through the ether, we amateur:
knew Of no coils except those wound
around and around a cylinder. These
two main kinds we're the loose coupler,
which is a small cylinder which slides
In and out Of n larger one, and the sin
gle cylinder with the insulation scrapcd
of OF path along the top, 80 that some
kind Of sliding device could be run along
it to make contact with the coil at any
part
The latter type then subdivided in two
great classes---the single slide coil and
the two slide. Some preferred one
some preferred the other. Still Others
would have nothing but the loose cou
pier.
All Of these devices. Of course. were
made for the purpose Of tuning the
set to different wave lengths.
Old-time amateurs who gradually
dropped out Of the game because they
never could master the dot and -ds sh
code (Which was the only thing we
heard slowed these tuners away In the
NgsJ dlu tepfLS VI Lue dtllt anu loESol
all about them, or else gave them to
their sons. who soon put them out OF
commission.
But broadcasting of music and speech
has revived the wireless interest Of most
OF these old timers and they have Won
dered II their old tuners would work
with the new audion bulbs. AS we have
already pointed out in these articles.
they can all be used. But the best of
! them. for use with the audion bulb, so
far as my own investigation shoes. Is
the two slide tuner. We have already
given the wiring instructions for its
adaptation to concert work. II you can
find your old tuner. just hook it up and
listen in.
If, however, you are a newcomer in
the fascinating game of wireless and
YOU want to install set as cheaply as
possible, you will find two slide tuner
an extremely cheap piece Of apparatus.
and it is. perhaps, the easiest to build.
An oatmeal boz, wound closely with
wire. with few little metallic gew.
gaws for purposes Of connections, be-
comes two slide tuner. A salt box
will do; cardboard mailing tube will
do. A section of rolling pin or a milk
bottle or anything shaped like a cylin-
der-and not made Of metal-will do.
For tuner of this kind you will ind
that enameled wire is by all odds the
best. Many writers advise silk or
cotton covered wire, but have found
that the silk and cotton unravel and
become nuisances in time. even If they
are we'll coated with shellac.
The wire that Is insulated With a
coating OF enamel is very cheap and
much easier TO work, besides giving
much better length of service. Use al.
most any size. from No. 80 to No. 20.
Smaller and larger sizes can be used.
but II Is best to get wire somewhere
around No. "a or thereabouts.
The tube should be from three and
half 70 four inches in outside diam
eter. 1t can be as much smaller as
you like. but the smaller il is the longer
It must be. Figure on four inch tube
about six or seven inches long as stand .
ard. II you get It larger you are going
TO sacrifice sharpness Of tuning.
I have one of those huge old "NAA'
tuners, six and a half inches in diam .
etcr and twelve inches long. that we
used 10 have to use In the old days to
get the time signal and press from Ar.
ltngton, Va, on 25OO meters wave
length. Hooked up in the audion cir