Radio Broadcast - 1925, February - 113 Pages ... - VacuumTubeEra

"NOW,
1
HAVE
FOUND. .
A Department Where Readers Can Exchange Ideas and Suggestions
of Value to the Radio Constructor and Operator
PR a long time, RADIO BROADCAST has felt the need of an outlet for the many excellent ideas dealing with
various features of radio construction which reach our office. With this issue, we begin the department
cf good ideas from our readers, and invite the cooperation of all those who are interested.
If you have an idea about a valuable and useful new circuit, some new device, a construction or operating
suggestion, we should like to have it.
Payment of from two to ten dollars will be made for every idea accepted.
The descriptions should be limited to three hundred words and typewritten. Accompanying sketches, drawings,
and circuit diagrams should be as plain as possible.
We do not want simple, obvious suggestions. Material to be acceptable for this department must offer
something of definite value to the constructor. Mere novelty is not desired. Address your manuscripts to
this department, RADIO BROADCAST, Garden City, New York. THE EDITOR.
A FORM FOR ROBERTS COILS
THE easiest way is to make a tin template
to start with, from which any
number of forms may be made, which
will be handy when your friends hear your
Roberts set and want to make one like it,
Cut a circular piece of tin 4^" in diameter;
drill, No. 44 or smaller. Drill the center hole
with a No. 19 drill. See Fig. i.
Cut out 5 pieces of -^ " either red or black
fibre 4^" in diameter and drill the center hole
with a No. 19 drill. Bolt the template to one
of the fibre pieces with an ^ screw and run the
small drill through the fibre using the holes in
the template to guide the drill. Take off the
TIN
9
/32*3"
$^\
#19 DRILL'
CENTER HOLE
FIG. 2
FIG.
I
then strike a circle on this piece 2\" in diameter.
Set the dividers a little less than \" and
starting at a mark on the 2\" circle, "step" the
dividers around the circle counting the steps,
the object being to make 15 divisions on the
circle. This will take several trials and some
patience.
When at last you have the dividers
set right, mark the 1
5
divisions and centerpunch
them. Drill them out with a small
FIG. 3