The Ely miner. [volume] (Ely, Minn.) 1895-1986, 1924-12-05
ey r. .. ROBBINS

BY r. ]. ROBBINS
Since the inception of the. new
tunable transformers for r. F. circuits
1t has been found desirable to devise
some method of mounting the various
units so that the angle from the YER
teal may be readily varied without
disnantling and redrilling panel sew
eral times. 1t is, of course, possible
to construct the Neutroformer in such
way that it can be mounted to the
panel by a single bushing in the center.
This is quite obviously the most prac-
teal method of getting around the
difficulty, and the writer has noted one
or two such makes offered for sale.
For the benefit of those who have to
contend with mounting screws and
other attendant evils the following idea
may be of some benefit.
There are probably as many diff
ferent makes of variable condensers
as there are breeds of dogs, so the
writer will make no attempt to make
this into a catalogue of all the ones
which may be used.
We will assume as a starter that an
angle of 40 degrees will be the medium
angle, and that the direction in which
the unit will revolve may be an equal
distance either to right or left of this
point. This enables US to place the
Neutroformer either in position near
ly vertical or nearly horizontal as de-
sired.
We will consider but two common
types of condenser and leave the rest
to the ingenuity of the reader Ii he
happens to have a condenser which
does not come within the specifica-
tions mentioned. The first is relative
to any type of condenser which mounts
by means of three or more screws, all
of which are located on a circle and
spaced equidistantly. This is exempli-
fed by the well known Federal, which
mounts with three screws, or the
Malone-Lemmon, which uses four. In
each case these are all located SYM
metrically as regards the center, which
opens up the possibility of changing
| the angle of the whole by very SIM
pie expedient. This consists of cutting
slots along the circle on which the
holes are laid out in which the screws
may slide smoothly. These slots are
| to be made 3-16 of an inch wide and
are all of the same exact length. 1t
| Is necessary that these be laid out
| very carefully with dividers and a
steel square.
How to Proceed.
The procedure will be roughly as
| follows:
1. Strike lightly the circle on which
the various holes are located.
2. Strike two more, one of radius
smaller by 1882 of an inch, the other
! larger by the same distance. The two
latter circles form the main outline
of the slots.
3. Divide the circle into quadrants
and bisect one of the angles TO obtain
45-degree angle.
| f. Working from the point on the
circle, set the dividerS so as to tri-
sect the circle. Cor divide in four If
there are four mounting screws).
8. Lay aside the large dividers and
get small pair, which set at about
one-half or five-eighths of an inch, ac-
cording to desired length of slot. Set
dividers at each of the three Cor FOUR
points previously located and step off
distances each side of the center
points.
6. Prick punch these points care
fully. Drill 3-16 of an inch hole at
each of these points, taking care that
drill does not creep in the. least.
These holes form the rounded ends
| of the slots, and the remaining ma
terial between each pair of holes
should now be carefully removed by
drilling out and filing until the finished
slots are perfectly smooth and the
screws will ride in them as the Neutro-
| former is turned. A 9-32 of an inch
hole is drilled in the center TO accom-
modate the shaft as usual. All that is
necessary now to finish the job will be
| to substitute round head 1872 machine
screws for the usual fiat heads. A
small washer on each will help to
preserve the edges of the slots. 1t will
| Low be found TO be simple matter to
turn the unit in the direction desired.