Hints and Kinks for the Experimenter
January 1967 QST Article
is not a word you hear very often anymore in reference to having a problem in a process or task, but it turns up
fairly regularly in hobby and do-it-yourself types of magazines as "Hints and Kinks" columns. Having a kink in the
neck or a kink in the garden hose are more familiar uses of the word. "Kink" appears in QST, my older model airplane
magazines, in some of the Popular Electronics magazines, and likely in many others. "Hints and Kinks" type columns
typically are collections of ideas submitted by readers explaining how they solved a particular problem or how they
came up with a new way of doing something. Some are outdated but many are timeless in their application and usefulness.
I put all the ones here in to the latter category.
of Contents]These articles are scanned and OCRed from old editions of the
ARRL's QST magazine. Here is a list of the
QST articles I have already posted. As time permits, I will
be glad to scan articles for you. All copyrights (if any) are hereby acknowledged.
Hints and Kinks for the Experimenter
|Final Tuning Knob for the Heath "Sixer"
tuning capacitor in the Heath Twoer and Sixer happens to be a ceramic trimmer not normally accessible from the
outside of the cabinet. In order to dip the final, one of two methods is usually used to reach the trimmer;
either the unit is removed from the case or a screwdriver is inserted in a hole drilled in the side of the cabinet.
However, this is not always so easily done, especially if one is working mobile. The author solved this problem
by making a built-in self-retracting knob which is always handy, but which is not in the way during removal
of the unit from the case. As shown in Fig. 1, the knob is not fastened to the trimmer and thus will not put
any strain on the capacitor or its associated wiring.
Fig. 1 - Details for assembling a final-amplifier tuning control for a Heath Sixer or
Begin the modification by drilling a 1/2-inch diameter hole in the case directly in
line with the trimmer adjusting slot. Make a 1-inch square plate from 16 gauge aluminum stock and drill a 11/64-inch
hole in the center of the square. Drill two 1/8-inch holes in the plate for mounting the plate to the case.
These holes should be a little bit on the sloppy side for the screws that will be inserted in them, since the
trimmer does not always return to the exact same spot each time the unit is put back in the cabinet. I used
screws from an old Command receiver to fasten the plate to the case. Drill two holes in the cabinet to mate
with the mounting holes on the plate, being careful to make the holes small enough to allow the screws to self-tap.
Chuck 1/4 inch of a 1 1/4-inch length of 1/4-inch diameter bakelite rod in an electric drill. Use a
file to turn down the diameter of the remaining 1-inch length of rod to 5/32 inch. File a screwdriver bit on
the face of the 1/4-inch diameter portion, as shown in Fig. 1. Mount the plate on the case and insert the bakelite
rod through the plate. Slip a 5/32-inch i.d. washer over the shaft, along with a small 5/8-inch long coil spring
and a suitable knob, such as the antenna trimmer knob from a Command receiver. Make sure there is enough compression
on the spring to keep the rod retracted. After all the parts are assembled and the unit is installed in the
cabinet, it is only necessary to push in the knob and rotate it until the shaft bit engages the slot of the
trimmer. - Frank M. Wing, W4TUO
Thumb-Groove Indexing the Handbook
of the Handbook that are frequently used by the reader can be located quickly by filing thumb grooves in the
Handbook pages as shown in Fig. 3 and labeling these grooves as pictured in Fig. 2. As illustrated in the second
sketch, I filed thumb grooves for only three subjects: the wire-size table, the tube index and the general index.
These items seem to fill 99 percent of my general requirements. Other grooves can be added at any time, but
usually the sections of the book they indicate are only of short-term use. - Norm Cucuel, K1LFH
Fig. 2 - K1LFH's method of thumb-groove indexing the Handbook.
Fig. 3 - One method of labeling the thumb grooves.
|Adhesive-Backed Terminal Board Eliminates Mounting Screws
low-profile terminal board shown in Fig. 4 is especially useful in dense electronic circuits where mounting
space and working space are limited, and where it may be undesirable or impractical to use mounting screws or
other hardware fasteners. The terminal board consist of 0.012-inch-thick copper terminal strips cemented between
0.032-inch-thick fiberglass sheets which have a thin layer of pressure-sensitive adhesive backing. Scoring between
terminal pairs facilitates detachment of the required number of terminals for specific applications. For soldering
connections, the copper terminals are bent outward. The boards are mounted by pressing the adhesive backing
onto a mounting surface in the equipment package. - NASA Tech Brief 65-10396
Fig. 4 - Details of the adhesive backed terminal board.
Football shoe cleats come in many varieties. The hard rubber and nylon types that are
threaded make good standoffs or feet for electronic equipment. Cleats are available from most sporting-goods
stores. - Karl Hatfield, W6BXR
Grommet Cable Holder
One way I have found
to make a chassis wiring job neater is to use rubber grommets as wire bundle holders as shown in Fig. 5. If
the approximate number of wires that will pass through each bundling point can be predetermined, it will be
easy to pick out the proper size grommets to secure a tight fit.
- Phil MacDonald, WA1CTQ
Fig. 5 - The rubber grommets, shown here as cable holders, should be chosen to firmly
secure the wires in neat bundles.
Phone-Jack Panel Bearing
in Fig. 6, a panel bearing can be made from all extra phone jack by filing away the flange on the inside of
the jack and removing the excess contacts, soldering lugs and phenolic insulation. The bearing will be suitable
for a 1/4-inch shaft if a standard phone jack is used for the modification. -John Wallace, WA5NPE
Fig. 6 - By filing away the flange and removing the excess parts, a phone jack (A) becomes
a panel bearing (B).
I have found that hose racks,
ordinarily used for the storage of garden hose on the side of a house, are ideal for keeping accumulated wire
and coaxial cable in order. Aluminum racks, which sell for about 75 cents each, make excellent spools for lightweight
wires and cables. Steel models cost approximately a dollar apiece and are useful for storing heavy cable such
as RG-8/U. Garden-hose racks are sold by most hardware stores. -Julian Lovejoy, W1BT
Inexpensive Signal Generators
inexpensive wide-range signal generators that use air-core coils
can be calibrated exactly, even though they don't have an individual calibration adjustment for each band. Stuff
a length of spaghetti tubing with aluminum foil and insert it into the coil to be adjusted. Slide the tubing
in and out of the coil until zero beat is achieved on a calibrated receiver. For best mechanical stability,
the tubing should fit snugly in the coil. - Lou Fuentes, WB2MYN
(Since an aluminum core lowers the inductance
of a coil, the above method of alignment will not work on those bands where the coils employed have too little
inductance. This situation can he corrected by the following technique: Switch the generator to the band which
is in error on the high-frequency side by the greatest percentage and fix the position of the tuning capacitor
at some convenient frequency. Unloosen the pointer and reattach it at the correct calibration mark. Proceed
to calibrate the other bands as suggested by WB2MYN. Observe, however, that the calibration points may or may
not be true across the entire scale. Also note that inserting aluminum foil in an air-core coil will lower the
Q of the inductor; in some cases, the reduction in Q of an oscillator coil might cause the circuit to cease
functioning. - Editor.)
Posted November 29, 2013