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Copyright: 1996 - 2024
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed
formulas and reference material while performing my work as an RF system and circuit
design engineer. The World Wide Web (Internet) was largely an unknown entity at
the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps
while typing up your telephone line, and a nice lady's voice announced "You've Got
Mail" when a new message arrived...
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Tricks of the Trade
1954 Popular Electronics
hobby magazine worth the paper its printed on has a "tricks of the
trade" type column. Popular Electronics started out its
very first issue in October 1954 with a column that went by exactly
October 1954 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
published October 1954 - April 1985. All copyrights are hereby acknowledged.
For some reason I did not scan and OCR the entire
article, but here are the first couple pages of tips. In looking
at the other missing page, I'd say nothing really useful was missed,
so unless someone specifically requests it, this is all that'll
It's good stuff to know, even in 57 years later
Tricks of the Trade
REMOVING BRAID FROM SHIELDED CABLE
cable, whether used in audio or r.f. work, always presents a problem
to the experimenter as stripping and removing parts of the braid
are not easy. A good technique is as follows:
If an outer
layer of insulation is used, remove a portion by running a sharp
knife around the cable, flexing it slightly to break the insulation
loose as shown in (A). Too much pressure on the knife may nick the
Loosen the braid with the fingers and push it back so that a
flat ring is formed as shown in (B). Using diagonal cutters, clip
the outer edges of the flat ring (C) thus separating the braid.
Remove the excess braid and strip a portion of the insulation from
the inner conductor as shown in (D) . . . . . . . L.G.
* * *
STRAIGHTENING BUS BAR
Bare, tinned copper
wire or "bus bar" is often used in commercially-built test equipment.
Unfortunately, this bus bar develops kinks and wrinkles if left
around the workshop bench and should be straightened before being
used in home wiring projects.
To straighten any sized bus
bar, from 22 gauge to 12 gauge, clamp one end in a heavy bench vise
and grasp the other end tightly with a pair of pliers. Now apply
a strong, steady pull on the wire. Use plenty of strength, but don't
pull too hard or jerk the wire as it may break. The wire will straighten
out nicely and may even stretch slightly. If this happens, the wire
diameter will be reduced and the wire will tend to be stiffer and
hold its shape better.
* * *
TERMINATING SHIELDED CABLES
shielded cables, such as microphone cable, as well as small sizes
of r.f. coaxial cable, may be terminated in a professional way by
using the method shown in the diagram.
If the cable has
an outer insulator, remove about 3" of this material as shown in
(A) thus exposing the braid. Next, push the braid back to loosen
it and bend the cable slightly. With a soldering aid, a scribe,
or a small nail start working the strands of the braid apart to
form a small hole as shown in (B). Keep working on the opening and
bending the cable until you can get the tool under the inner conductor
(C). Now slip your tool under the inner conductor and pull the free
end out of the braid (D). Hold the edges of the braid back with
the fingernail, if necessary, while performing the operation.
With the inner conductor free of the braid, stretch the braid
out until the opening is closed tightly around the inner conductor
(E). Finally, finish the job by stripping insulation from the inner
conductor and flatten the extra length of braid to form a ground
strap as shown in (F)
* * *
A Self-Tapping screw, suitable for use in
aluminum, as well as Bakelite, lucite, polystyrene, and other plastics,
may be made in a few minutes from a conventional machine screw.
Using a steel machine screw of the desired size and length,
run a nut up on the screw, almost to the head, as shown in (A).
Next clamp the screw and nut in a vise and taper the end (B) using
a flat file. Then, using a triangular file, file three or four tapered
notches along the screw. The notches should run the length of the
screw as shown in (C) and be deep-est at the end farthest from the
Finally, remove the nut, as shown in (D), thus restoring any
* * *
Too-Long machine screws
may be shortened by following a few simple steps. First select a
steel nut to fit the screw, then run it up on the screw past the
part to be cut off.
Clamp the screw and nut in a vise, cut
off the unwanted portion, using either bolt cutters or a hack saw.
Remove sharp burrs with a few passes of the file and then remove
the nut. As the nut is run off the screw, the damaged threads will
* * *
foil is a handy accessory to have in the home workshop for trouble-
shooting chirps and whistles in superhets due to insufficient shielding.
Every "new-born" home-constructed superhet receiver seems to have
at least a couple of these hard-to-clean-up bugs.
the set on a sheet of foil and fold up the ends to determine whether
shielding the entire chassis will help. Form the foil into temporary
tube and coil shields and put barriers of the foil between any components
suspected of feedback.
This is much faster than the usual
procedure of setting up permanent shields and then removing them
when they don't seem to help. When components feeding back are found,
isolate them entirely with conventional shielding. Always be sure
to ground all shields-permanent or temporary.
* * *
Recently I found it necessary
to shield a small superheterodyne oscillator coil. Since none small
enough for the purpose was on hand, I used the zinc can from a flashlight
Simply cut the can with a hacksaw close to the positive
end of the cell, grasp the cloth lining with pliers, tear out, and
clean the inside of the can. Cut holes for the leads and lugs for
Penlight cells make good subminiature
shields for portable radios.
* * *
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