Radio Broadcast (May 1928-Apr 1929)

New Apparatus ~T) RODUCTS of radio manufacturers -L whether new or old are always interesting to our readers. These pages, a feature of Radio Broadcast, explain and illustrate products which have been selected for publication because of their special interest to our readers. This information is prepared by the Technical Sta ff and is in a form which we believe will be most useful. W e have, wherever possible, suggested special uses for the device mentioned. It is of course not possible to include all the information about each device which is available. Each description bears a serial number and if you desire additional information direct from the manufacturer concerned, please address a letter to the Service Department, Radio Broadcast, Garden City, New York, referring to the serial numbers of the devices which interest you and we shall see that your request is promptly handled. — The Editor. A 1 2-Condudor Cable for A. C. Sets X47 Device: Yaxley Cable Type 612. A 12-conductor cable designed for use with a.c. receivers. The twelve conductors are arranged as follows: liV No. i— Red No. 2 — Black 2§V No. 3 — Red, with Green Tracer No. 4 — Black, with Green Tracer 5V No. 5 — Red, with Yellow Tracer No. 6 — Black, with Yellow Tracer B— No. 7— Yellow B+ Detector, No. 8— Blue B-f Intermediate, No. 9 — Slate B+ Amplifier, No. 10 — Green B+ Power, No. 1 1 — Brown Spare, No. 12 — White The plug terminals on the mounting plate are plainly numbered in white. The individual conductors in the cable are colored as is indicated above. In addition, each conductor is also numbered, 1, 2, or 3, etc., to correspond to the numbers of the plug terminals on the mounting plate. In this way it is a simple matter to make the proper connections. Manufacturer: Yaxley Manufacturing Company. Price: $5.00. Application: This cable may be used in cases where the transformer supplying the filaments of the a.c. tubes is not located in the set, but with the B-power unit. In such a case it is, of course, necessary to use connecting wires between the set and the filament transformer as well as to provide leads for the B voltages. This requires a 12-conductor cable such as we have described. STERLING TUBE CHECKER Resistors for B Supply X 48 Device: Vitrohm Resistor Kit for use in Bpower units. A set of eight separate resistors as follows: 1 750-ohm, 3 1500-ohm, 1 3000-ohm, 1 3500-ohm, 2 5000-ohm. Each resistor measures about 2 inches long. Manufacturer: Ward Leonard Electric Company. Price: $8.90. Application: The resistors are of such a size and rating that they may be satisfactorily used as voltage-dividing resistors in B-power units delivering voltages up to 500 volts. The two circuits, Fig. 1, A and B, show how the resistors can be used in two B-power circuits, one delivering up to 135 volts and the other supplying 400 volts. The 135-volt circuit makes use of only four of the resistors. If the experimenter so desires he can make use of all eight units and obtain some additional B-voltage taps at intermediate voltages between 135 volts and 22 volts. As mentioned above these resistors are of such values that they can be applied to any ordinary B supply. ■ From Filter System ^/WW lAWA^-^W^WV^AMAA, 750 ohms 1500 ohms 1500 ohms 3500 ohms 11,500 ohms Usel-750 I Usel-1500 e Usel-1500 J Usel-3500 i Usel-1500 t 7 ohm resistor i ohm resistor * ohm resistor + ohm resistor + and 2-5000 + 28 22 42 80 ohmresis-400 tors in series (A) From Filter System 1500 ohms Usel-1500 ohm resistor 1500 ohms Usel-1500 ohm resistor v"\AWVW\A -VWWWv^ -A^AAA/VW -AA/WWWV 3500 ohms Usel-3500 ohm resistor 3,000 ohms Use 1 -3000 ohm resistor 90 135 <B> YAXLEY CABLE FIG. I. B-SUPPLY RESISTOR BANKS A Handy Tube Tester X49 Device: Tube Checker. An easily operated, low priced, rugged instrument with which to check all types of tubes for short circuits between the elements, and to check the emission of a.c. tubes and 199 and 120 type tubes. To operate the unit the plug is connected to a 1 10volt light socket and the tube to be tested is plugged into the tube socket on the tester. The meter immediately indicates any defect in the tube. Manufacturer: Sterling Manufacturing Company. Price: $13.50. Application: This instrument is a convenient method for the radio dealer or service man to use when selling tubes to a customer, for it can be used to show that the tube being sold is in good condition. It will also be valuable in the repair department or in the hands of the service man. 227 Coils for Short-Wave Work X 50 Device: Short-Wave Coils. A set of three coils to cover the band of wavelengths from 13 to 130 meters. Additional coils can be obtained to cover wavelengths up to 550 meters. The coils, illustrated in the photograph, are of the plug-in type, different ranges being covered by changing the secondary-tickler coil. The same primary is used for all wavelengths. The coils are wound with a large size of wire so as to give them considerable mechanical strength. The coil diameter is 2 inches. Manufacturer: Aero Products, Inc. Price: $12.50 for a set of three coils covering the band from 13 to 130 meters. Two additional coils, sold separately, may be used to reach up to the broadcast band. These coils are $4.00 each. AERO SHORT-WAVE COILS Application: The coils may be used in the construction of a short-wave receiver to receive code and short-wave broadcasting. The plug-in base and primary coil mounting are of the same dimensions as were used for previous types of Aero coils, so that either new or old coils may be used interchangeably in the same mounting. A Way to Remedy R. F. Oscillation X51 Device: Phasatrol. A device designed for use in radio-frequency circuits to control oscillation. The unit is connected in the plate circuit of an r.f. amplifier tube and the adjusting screw is then turned until the circuit is stable over the entire broadcast band. Manufacturer: Electrad, Inc. Price: $2.75. Application: The item to which we have here brought the reader's attention is not new, but some information regarding its use should be of interest to readers not acquainted with the device and to those not realizing that it may be applied to a wide variety of circuits. The performance of the unit depends, to some extent, upon the fact that if the plate load on a tube is made non-reactive (ordinarily its reactance is inductive) the tube cannot oscillate. Although the device does not give an exact "bridge" balance, it is much more simply adjusted than a bridge system, and can be readily applied to existing receivers. The device can be used to stabilize the intermediate-frequency amplifier of a super-heterodyne. It can also be used in such receivers as the Equamatic, the Bremer-Tully Counterphase, Roberts receivers, all tuned r.f. sets, etc., and its application to such circuits is fully covered in the circular supplied with it. Readers owning such receivers, or similar ones, which cannot be prevented from oscillating, can use a Phasatrol to overcorn e the difficulty. THE PHASATROL