Radio age (Jan 1927-Jan 1928)

RADIO AGE for November, 1927 Channel swim was scooped on short waves before other mediums could function. All this is free to him who has a short wave receiver. The only requisite is a knowledge of the code. This is easy to master. Concientious endeavor will familiarize one to such an extent the funny buzzes cease to be static and become letters spelling words, connected together into sentences. It is a great thrill to hear a mess of dots and dashes slowly evolve into a serious statement that an expedition has just discovered something new, or a great catastrophe has befallen someone. Those of us who heard the Dallas Spirit fall know this only too well. The results are worth the effort. Before any signals may be heard a receiver must be built, so let us roll up our sleeves and get busy. The parts selected are those which have proved their worth time and again. They are all standard and may be obtained on the open market. We chose them carefully, picking those which performed best in the combination of the finished receiver. Now that all the parts contained in the list are on hand we will lay out our panel and baseboard. This should always be done before a single hole is drilled. Quite often it will be found that a certain instrument must be moved a fraction of an inch to make room for another. If it is already mounted this cannot be done without leaving unsightly holes. The only correct way to lay out a panel is by using a square and a pair of dividers. It is slow and often tedious, but the results are accurate. We have already done this, and the readers may avail themselves of RNTENNA List of Parts and Accessories One set of Chirad Short Wave Coils. One Remler 639 Condenser, .0005 mfd. One Remler 659 Condenser, .0001 mfd. Two Remler Left Hand Drum Dials, No. 110. One Remler 35 Choke Coil. Two 530 Frost Sockets. One 1920, 20 ohm Frost Rheostat with switch. Two 235 Frost Cord Tip Jacks. One Thordarson R-151 6-1 Audio Transformer. Eight XL Push Top Binding Posts, marked as indicated. Two Benjamin 8629 Shelf Supporting Brackets. One Sangamo .00025 Grid Condenser with Clips. One Lynch Metalized Resistor, 3 Megohm. One 7 x 18 x 3-16 inch Rubber Panel. One 4 x 18 x 3-16 inch Rubber Subpanel. Ten Feet Square Tinned Bus Bar. Two 201-A Tubes. Two 45 volt B Batteries. One 414 volt C Battery. One Six volt Storage Battery. Headphones. Connecting wire, nuts, screws, etc. our efforts by obtaining the drilling templets supplied by the service department of this publication at a cost of twentyfive cents. Paste this templet to the panel and with a centerpunch and hammer make an indentation for every hole. Care must be used, both to make sure the impression is in the correct spot, and also that a light enough blow is struck not to crack the panel. The correct size drill is indicated, as well as countersunk holes. Rubber is used for panel and baseboard because it is the best dielectric obtainable in workable form, and it is far easier to handle than other insulating materials. The instruments to be mounted on the panel are the two tuning condensers, the rheostat and cord tip jacks. Next we will fasten the two brackets to the panel, and in turn subpanel to them. The chassis is now complete, ready for the instruments to be mounted. It will be noted that the coil jacks are removed from the supporting strip furnished by the manufacturer and placed directly in the subpanel. This shortens the leads considerably, makes a neater set and allows all the connections to be made on the under side. The grid condenser and leak are mounted on the under side of the subpanel, placing them in a position where the leads will be shortest. Mounting screws are furnished with the condenser, as well as clips to contain the gridleak. Surface mounting sockets are used, for as many leads are above the subpanel as below and it is just as easy to have the leads going down as it is to have them coming up. In wiring, about five lengths of square (Continued on page 36) S.MEG R.F.CHOKE Schematic diagram of the Radio Age Short Wave Receiver