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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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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April 1935 Short Wave Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Short Wave Craft was published from 1930 through 1936. All copyrights are hereby acknowledged. See all articles from Short Wave Craft.
Are you a project builder? If so, then you probably make a point of reading hints and tips offered by fellow do-it-yourselfers. Even with the ready availability of just about anything you need already pre-manufactured, there are still times that you either just want to figure out a better way of doing something or happen to have a challenge that does not have a solution that can be purchased from a catalog or on eBay. I have posted a few DIYer features from some of the vintage electronics magazines, many of which are still relevant, or might at least give you an idea for how to accomplish your goal.
$5.00 for Best Short Wave Kink
The Editor will award a five dollar prize each month for the best short-wave kink submitted by our readers. All other kinks accepted and published will be awarded eight months' subscription to Short Wave Craft. Look over these "kinks" and they will give you some idea of what the editors are looking for. Send a typewritten or ink description, with sketch, of your favorite short-wave kink to the "Kink" Editor, Short Wave Craft.
$5.00 Prize Winner
I am submitting a short-wave kink which I have found truly practical and very efficient. It is a band-spread kink which is truly automatic and which changes condensers when the different plug-in coils ale inserted. This system is really very flexible and may be varied to suit the fancy of the builder. Connections of the secondaries and ticklers are shown for five different bands: C is regeneration condenser, .00025 mf.; C1, a condenser to spread 20- and 40-meter bands; C2 will spread the 80- and ten-meter band; C3 covers the broadcast band. - Wm. Porter.
Many experimenters have had occasion to need a tool which has been magnetized in order to retrieve screws, nuts, or washers which have been dropped in the process of assembling radio apparatus. The drawing shows how a screwdriver or similar implement may be magnetized by bringing it in contact with the "pole-piece" of a dynamic speaker. Of course the speaker must be running in order that it will be magnetized. This stunt will only work of course on iron or steel tools and it will attract only like metal. Brass, copper, or aluminum will not be attracted to the magnetized screwdriver, of course. - Luther Burkhardt.
If a suitable lead-in insulator is not on hand, one can be constructed from a pair of regular stand-off insulators by the following method: Remove the fittings from two of these insulators and procure a length of 3/16-inch threaded brass or copper rod, 4 1/2-inch fiber washers, 6 nuts to fix the rod and a length of 1/2-inch glass tubing; also make two rubber washers 3 inches in diameter with a. 3/4-inch center hole. These can be cut from an old inner tube. I am using a pair of these insulators for bringing in a transposed lead-in and I find them very satisfactory. - John Schlener, Jr.
When making plug-in coils, especially the ones with larger windings, I found that the usual tube base was too short, In the drawing it can be seen that two tube bases are used; by removing the pins of one and cementing it in the top of the other, we have a very neat coil form.
It is necessary, however, to wind the required number of turns on the lower coil form before the two forms are cemented together. Then wind the other form and run the two ends of the wire down through the holes which were left when the prongs were cut off. The drawing clearly shows how the entire unit is assembled. - Milton Sarchett.
There are many times when I have found that a socket could not be mounted in the way it was designed for, and have found that it was possible to turn it up-side-down and overcome the difficulty. A sub-panel socket or wafer socket can be turned upside-down and mounted on top of the panel as shown in the drawing. Of course, all sockets, due to their peculiar contact construction will not work this way. However, I have found that 90% of them will. I have also found that the base-mounting socket could be mounted underneath the sub-panel by replacing the screws which hold the contact and face them downward. - S. Javna.
Undoubtedly nearly every experimenter who reads this magazine can find a large number of discarded old-fashioned phone jacks in the junk box. These should be saved by all means because they can be put to various uses such as shown in the accompanying drawing. In the drawing we have the base of the jack forming an "L" bracket which can be used for mounting midget condensers, volume controls, switches, and a number of other instruments. - James Slocum.
How many times have you broken the terminal on your last tube socket? This happened: to me one time and as I could not obtain another socket immediately, I had to devise a method of repairing the: damaged one. After much thought, a No. 5 soldering lug was finally brought to play. This was attached to the under side of the socket with a drop of solder and presto, the socket was as good as new! However, you will find that most of the metal parts on sockets are nickel-plated and it will be necessary for you to scrape the nickel-plated rivet until all nickel plating is removed and the brass or other metal shows through, otherwise the solder will not adhere to it. When you are in a "jam" for a socket some time, try repairing your old ones in this manner and see how nicely it works out. - Edward Kolakowski,
After completing a 4-tube short-wave receiving set I found, much to' my disappointment that it was an excellent receiver of passing automobiles-ignition noise, of course! The next move was to completely shield the receiver but funds were low so the idea, presented in the drawing, came into being. The cabinet I used was made from an old wash boiler which, incidentally, is copper and provides very effective shielding. The removable cover offers ease in getting at the inside of the receiver for changing coils or tubes. A shielded power cable was also used in order to eliminate pick-up. This in connection with the thorough shielding and the use of a good antenna, practically eliminated the interference. - C. E. Judson.
Experimenters who have found difficulty in making a neat binding post connection, when using stranded hook-up wire, will find this odd wrinkle a cheap method or making positive contact. A number or eyelets (obtainable at any stationery store) and a pair of pliers comprise the necessary equipment. First, twist the strands of the end of the wire to be connected and loop this terminal about one of the eyelets; clamp the eyelet firmly to the pliers, and it will be found that the end or the wire is being gripped between the two sides of the eyelet. The latter can then be slipped on and off the binding post rapidly, and without danger of the wire being forced from under the head of the post, as often occurs when using stranded hook-up wire. - Walter Kells.
Brass Wheels are put on the two shafts of band-spreading condensers. This is simple enough but the detector band-spreading condenser's shaft will have to be removed and a 4-inch shaft inserted so that shaft may reach the new dial on the new panel. The brass wheels are now tied together by means of a piece of good fishing twine as shown in the sketch. If one prefers, the twine may be replaced by a metal strip similar to the one used in the Atwater Kent receiver. If twine is used a knot is made about the pin in each of the brass wheels. - Francis E. McGee. W3DM.
By cutting off and bending Fahnestock clips, as shown in the drawing, a very handy plug-in coil receptacle can be constructed. The drawing shows the method used in mounting these clips. The contacts for the coil are ordinary machine screws which are allowed to protrude and fit in the slot of the clip. The clip is to be formed so that when the coil is pushed down into them they will bear similarly against the nut which holds the screw to the coil form. Two windings are shown on the coil; however, this could be increased to three or four windings with a consequent increase in the number of clips. - Wm. H. Eaton.
Posted February 19, 2015