Radio Broadcast (Nov. 1925-Apr 1926)

364 RADIO BROADCAST ADVERTISER Better Tone! with Dry Cells and UX 120 than with Storage Batteries _ Note: The UX 120 is a new three-volt dry battery power tube. Used for audio frequency amplification, this lube will produce better quality and greater loud speaker volume than regular storage batterv tubes. Any set owner can easily install a UX 120 tube in his set in a few minutes by using the new Na-Ald Number 120 Connectorald. It is a simple, efficient means of introducing the necessary additional "B" and "C" voltage required for this tube into the plate and grid circuit without rewiring the set. As easy to use as an adapter. Just slip the Connectorald onto the UX 1 20 tube and put the tube in the socket. Connect the batteries — and — well, that's all there is to it. Except to enjoy a quality and volume you would not have believed possible. No need to fuss with charging batteries. The simplicity, economy and freedom from attention characteristic of dry cells is now combined with the real volume and quality previously obtainable only with storage battery tubes. The No. 120 Connectorald is suitable for all sockets — metal neck as well as insulated. For sale at radio, electrical and hardware stores. Price, $1.25. NA-ALD ADAPTERS Na-Ald Adapter 419-X With this adapter the Na-Ald de Luxe Socket will take the new UX 199 small base tube. Price, 419-X, 35 cents. Na-Ald 420 Connectorald No. 420, equipped wilh cables, enables owners of Badiola Super-Hel to net the great increase in volume and clarity the new fXY-120 lube develops. Price, 420, $1.25 Na-Ald Adapter 421-X No. 421-X makes possible the shift from WD-U to UX tubes. Especially designed to enable owners of Radiola III, and 1II-A to enjoy the improved operation the new tubes provide. Price, 75 cents. All Na-Ald products are for sale at radio, electrical and hardware stores, everywhere. Send for complete data on adapters for new tubes. Alden Manufacturing Go. Also makers of the Famous Na-Ald Sockets and Dials Dept. B14 Springfield, Mass. Alden Processed IA-ALI Sockets and Dials j ampere, use a6-ohm rheostat for a secondary voltage of 6 volts; use about a 25-ohm rheostat for any voltage between 6 and 10 volts. For a tube requiring a filament current of one ampere, a 6-ohm rheostat may be used for any voltage up to 10 volts. I have used plate voltages as low as 67 volts on both amplifier tubes with satisfaction. The optimum value of plate voltage for the detector tube can best be found by experiment, and for the three-volt tube wiil be about 40 volts. John B. Clothier, Jr., Lansdowne, Pennsylvania. A HOME-MADE LOUD SPEAKER THE main difficulty in loud speaker horn construction lies in cutting the parts to fit, and in obtaining well proportioned lines and acoustics, which will be a credit to the finished product. A brief study of the patterns and details given below, will enable anyone to build easily a horn which will be very satisfactory with an audio-frequency amplifier. It is constructed almost entirely of 0 inch fibre or cardboard, and the dimensions for the various pieces are outlined in Fig. 2. The back, A, is cut from a piece 9 inches wide and 24 inches long. A line drawn through the center and perpendicular to the 9-inch side, will aid in making the nine measurements, one every three inches, to secure the curves indicated. The two sides, B, and back, C, are likewise laid out and cut with a sharp knife. The four parts are fitted together by lapping A and C over the two sides, B, beginning at the bell end and taking one corner at a time and bending to conform to the curves and fastening, wherever necessary, with a few stitches of No. 26 copper wire, which is threaded through perforations near the edge. After all corners are fastened, four strips of strong paper, 4 inches wide, are cut to fit each corner. These are creased lengthwise, THE FINISHED SPEAKER scored where bends cause wrinkles, and pasted on smoothly. To assist in making the base, D, a circle 14 inches in diameter is drawn on a piece of cardboard. This is then marked, cut, scored on the dotted lines, bent over a sharp edge and the seven f-inch woodstrips tacked in at the corners. Four of these may be used if desired. A J-inch hole is cut in the center of the base for a No. 522 CW Western Electric Loud Speaker Unit. The base and horn are then fastened together with moulding and small brass screws, and the whole given four coats of paranite. Paranite can be made by dissolving parts of an old phonograph record in denatured alcohol. It strengthens the horn and gives it a very desirable velvet black finish. The unit is fastened in the base by first inserting the rubber bushing to a tight fit. (Continued on page 374) x V2 Moulding ^ and Bottom Strips FIG. 2 ■jr Tested and approved by Radio Broadcast it