Radio Broadcast (May 1928-Apr 1929)

RADIO BROADCAST'S TUBE DATA CHARTS — II SYLVANIA PRODUCTS COMPANY THE users of vacuum tubes have a right to expect two things from the manufacturer of the tubes; first the proper characteristics at the start of their life, and secondly a long life. Life tests were made in Radio Broadcast's Laboratory on several makes of tubes. The life tests consisted of running the filaments of the tubes from a.c. and putting 100 volts d.c. from a generator on the plate with the grid left free At the end of each hundred hours each tube was taken off test and its plate resistance and amplification factor measured on a tube bridge. The amplification-factor measurement gave an indication of any change in the internal arrangement of the tube elements, the test of the plate resistance indicated whether or not the emission of the filament was falling off. It is a fact that Sylvania tubes not only had the correct characteristics at the start of such a life test and held them throughout the test, but the majority of the tubes tested actually decreased slightly in plate resistance, and thereby had a some £ 1.0 4.0 s < -0.5 2.0 0 Fig. 2 RADIO BROADCAST LABORATORY ,.r.ar.;3 Eg= 3A-k o s ! \ 1 u\ Plate A* Ail, \ 0 1.0 2.0 3.0 1.0 2.0 3.C EF VOLTS EF VOLTS 19000 18.000 17,000 16.000 15,000 14,000 13,000 i 12.000 0 11,000^10,000 9000 8000 7000 6000 5000 on the Sylvania eighth-ampere general-purpose tubes, the SX-201B tubes, prove them to have as good or better characteristics than the average quarter-ampere tube of the 201A-type. Some characteristic curves of Sylvania a.c. tubes of the heater and filament types are shown in Figs. 1 and 2. These data are plotted against heater volts Eh, for the SY-227 tube and against filament volts, Ef, for the SX-226 tube. They show the futility of running these tubes at voltages beyond their normal rating, and prove that voltages slightly under rated values will produce practically identical characteristics. For example, the plate resistance (Fig. 1) of the SY-227 at a plate potential of 90 volts with a zero grid bias is approximately 10,000 ohms when using a heater potential of 2.25 volts; with the same grid and plate voltages the plate resistance is about 8500 ohms at normal heater temperature. 1.0 2.0 E„ VOLTS 2.5 3.0 EH VOLTS what higher mutual conductance at the end of 1000 hours than they did at the start of the test. Tn other words the tubes improved. The curve in Fig. 3 shows the average tube of the lot. Its starting resistance was 12,700 ohms, and at the end of 1500 hours when the test was discontinued the resistance had decreased to 12,000 ohms or about 6 per cent. The Sylvania Company makes 19 types of tubes, including two special detectors, the SX-200A and the SX-200B. The latter is an eighth-ampere special detector tube. Both are caesium vapor tubes, and get special care in manufacture and test. With each special detector tube is packed a certificate which guarantees "greater distance receiving range anil more volume in the reception of weak signals than any other tubes." Characteristic curves made in the Laboratory Fie, 3. HOURS IN LIFE TEST AVERAGE CHARACTERISTICS OF SYLVANIA RADIO TUBES TYPE USE BASE HEIGHT (Max) DIAM. (Max) FILAMENT SUPPLY SOURCE VOLTS AMPS. PLATE VOLTS DETECTOR AMPLIFIER PLATE mA. AMPLIFIER GRID VOlTS AMPLIFIER PLATE RESISTANCE (OHMS) AMPLIFICATION FACTOR MUTUAL CONDUCTANCE MICR0MH0S SX-201-A Detector Amplifier 4"/,fi 1 'Me Storage 6 V. 5.0 0.25 20-45 45-135 1.0 to 3.0 0 to 9.0 11,000 8.5 725 SX-201-B Detector Amplifier 4 "/,* 1 'M£ Storage 6 V. 5.0 0.125 20-45 45-135 1.0 to 3.0 Oto 9.0 11,000 8.5 725 SX-200-A Detector 4 Hie 1%" Storage 6 V. 5.0 0.25 20-45 Detector 1.0-1.5 30,000 20.0 680 SX-200-B Detector 4 'Me" 1% Storage 6 V. 5.0 0.125 20-45 Detector 1.0-1.5 30,000 20.0 680 SX-112-A Semi-Power Amplifier 4% 1 'Me Storage 6 V. A.C.5V. 5.0 0.25 90-180 5.5 to 13.0 6.0 to 12.0 5,500 8.0 1500 SX-171 Power Amplifier 4'y1( 1 'Me" Storage 6 V. A.C. 5 V. 5.0 0.50 90-180 10.0 to 20.0 16.5 to 40.5 2,200 3.0 1400 SX-171-A Power Amplifier 4 7i6" 1 'Me" Storage 6 V. A.C. 5 V. 5.0 0.25 90-180 10.0 to 20.0 16.5 to 40.5 2,200 3.0 1400 SX-240 Det-Amp. Res.Coupling 4 i/16" 1 ,346 Storage 6 V. 5:0 0.25 135-180 135-180 0.1 to 0.3 1.5 to 4.5 150,000 30 200 SX-199 Detector Amplifier 4 V 1 3/le Dry Cells 4.5 V. Storage 4 V. 3.3 0.06 20-45 45-135 1.0 to 3.2 0 to 10.0 15,500 6.6 425 SV-199 Detector Amplifier 3>s" 1 Me" Dry Cells 4.5 V. Storage 4 V. 3.3 0.06 2045 45-135 1.0 to 3.2 Oto 10.0 15,500 6.6 425 SX-120 Power Amplifier 4 H " 1 He Dry Cells 4.5 V. Storage 4 V. 3.3 0.125 135 6.5 22.5 6,300 3.3 525 SX-226 Amplifier 4 'Ms 1 'Me A.C. 1.5 V. 1.5 1.05 90-180 3.5 to 7.5 4.5 to 15 7,400 8.2 1100 SY-227 Detector 4'V-,6 1 'Me A.C. 2.5 V. 2.5 1.75 20-90 90-180 3.0 to 7.5 6.0 to 13.5 10,000 8.2 900 350 650 SX 222 Amplifier 5 V 1 'Me" Dry Cells 4.5 V. Storage 4-6 V. 3.3 0.132 135-180 1.5 1.5 850,400 300 SY-222A.C Amplifier 5 V 1 'Me" A.C. 2.5 V. 2.5 1.75 135-180 5.0 1.5 200,000' 150 SX-210 Power Amp. Oscillator 6% " 2 Me" A.C. 7.5 V 7.5 1.25 250-425 10 to 18 18-35 5,000 8.0 1600 SX-250 Power Amp Oscillator 6\" 2 'Me A.C. 7.5 V 7.5 1.25 250-450 28-55 45-84 1,800 3.8 2100 Model Use Base Height (Max) Diam. (Max) Filament Plate Supply Source SX-281 Half-Wave Rectifier 6Vl 2 Me A.C. 7.5 V. SX-280 Full-Wave Rectifier 5H" 2 Me A.C. 5 V. Volts 7.5 5.0 Amps. Max A.C. Volts 1.25 750 2.0 300 per Plate Max D.C. mA. 110 125 Both Plates Notes: Where only one set of characteristics is given these apply to the mean or most used values of plate and grid voltages. Bases will be designated by the following letters.according to their styles: X = Standard Push Type.Four Long Prongs. V= Old Navy Type Four Short Prongs Y = Push Type, Five Long Prongs Advertisement • march, 1929 . . . page 338 • Advertisement