The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1923-08-03
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meters. Other wave-lengths can be
estimated from these figures.
The wave-length will depend con-
siderably upon the size of aerial
used, also the capacity of the con-
densers. The variable condenser on
the primary should be of 0015 M. r..
and should be arranged with switch
so it can be connected either in series
or in parallel. The secondary vari-
able condenser should be of O01 NJ. f.
After the coils are wound, cover
strip will improve the appearance.
This is made from thin fiber-board,
but cardboard can be used. A row
of diamond-shaped holes should be cut
along the center of the strip. The
strip is then glued on and wrapped
with Irvine until the glue has set. The
winding will project slightly over the
edge of the tubing, so the cover strip
should be made slightly wider than
the tube. After the cover is glued
on and set, remove the Irvine and
smooth the joint in the cover with
sandpaper. The coil should then be
dipped in white shellac Of the best
grade, or better still, celluloid varnish.
which can be made from the following
formula:
Amyl acetate .................. 1 pint
Fusel oil 'refined) .............h pint
Benzi1e ..-.-............. pint
Wood alcohol MISUNDERSTANDING pint
10 oil 4 nun
Soluble cotton ................2 ounces
Add chemicals in order given, solu-
BILE cotton being last Allow to stand
II hours and strain through cheese
cloth.
After the coil has been dipped and
is dry, the varnish should be scraped
from the contacts and they should al
ways be kept clean and bright 1t is
good idea TO mark each coil with
the number of turns before varnish-
ing.
The Coil Mounting.
The mounting for these coils, some
times called the mechanical coupler.
is quite simple, as will be seen from
"
tionary while the other is movable
for the coupling. The round blocks
should be turned same size as the
block used in winding. The con-
facts are thin spring brass. A SLOT
is cut in the side of the block and the
contact fastened with a small screw
and bent back over the screw after the
lead wire has been soldered. 1t should
be quite springy and project slightly
from the block, which will insure good
contact when the coil is slipped in
place. BY making the contacts an
inch or more long, they will always be
in contact with the coil, even If it be
turned one way or the other in plac-
ing it on the block.
The dimensions of the arms need
not be exactly as given, but should
be long enough to allow the larger
coils to be used. An ordinary brass
hinge is used on the movable arm;
brass screws should be used in all
places, as iron screws would have
some effect on the working Of the coils.
Instead of using a base, the arms
can be mounted directly on top OF
cabinet, and the knob allowed to pro-
ject over the panel, which makes
convenient position for operating. II
it is desired to use three coils instead
of two, it is only necessary to add
another movable arm. The stationary
coil should be left in the center. Flex-
ible leads must be used on the nova
BILE coils and these should be soldered
to the contacts. The knob for ADJUST
ing the coupling is not absolutely
necessary, except in certin hook-ups
where the hands Of the operator have
a capacity effect.
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