The Challis messenger. (Challis, Idaho) 1912-current, 1924-12-17
BY r. j. 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
dismantling and redrllling panel sew
eral times. 1t Is, of course, possible
to construct the Neutroformer In such
way that 1t can be mounted to the
panel by 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
pther 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 As 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
Nd a
to the ingenuity of the reader II he
happens to have a condenser which
does not come within the specifica-
lions 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 20 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 1872 of an inch, the other
larger by the same distance. The two
latter circles form the main outline
of the slots.
8. Divide the circle into quadrsnts
and bisect one of the angles to obtain |
a 45-degree angle.
4. 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)-
5. Lay aside the large diyiders and
get small pair, which set at about
one-half or five-eighths of an inch, &C
cording to desired length of SLOT Ser
dividers at each of the three Tor FOUR
points previously located and step off
distances each side of the center
points.
6. Prick punch these points care
fully. Drill a 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-S2 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
70 substitute round head $50 machine
screws for the usual fiat heads A
,mall washer on each will help to
preserve the edges of the Slots 1t will
low be found TO be a simple matter to
urn the unit In the direction desired.
md after locating the correct angle to
tighten the mounting screw securely In
place.
Other Type Of Condenser.
The other type of condenser is the
form as exemplified by l
he Sleeper, U. S. Tool. Signal, etc.
These all mount by means Of two
crews located on a line one-quarter q
Il an inch Offset from the center line.
The method Of applying this Idea c
o such condensers is very similar to a
hat outlined above for the Federal. I
n this case the vertical and horizon a
nj center lines are drawn first and Il