Laboratory Jottings

Radio Record, Volume II, Issue 52, 12 July 1929, Page 32

Laboratory Jottings

Osram Valves and Ferranti Products

‘Osram Valves. A NEW full-revised series of Osram valves have been brought out by the British General Blectric Company: From their Wellington agents we have received samples of the 6-volt type. The following is a table of the Osram valves now on the market. We have tested the following valves: DEH610--This is a valve for use with a resistance-coupled amplifier, but used as a detector, it is very satisfactory. It oscillates freely on ‘low voltage and is capable of feeding to the amplifier a wide undistorted range. DELGIO-This is a general-purpose valve which can be used satisfactorily as R.F., detector or audio. It is capable of handling the output of a 3valve set without distortion. Correctly biased, with 3-volts it will deliver a current of about 8 milliamperes. ms nn = ee a A

‘DEP610-This is a very fine valve, suitable for use in the last stage of a multi-valve receiver. It does not appreciably decrease volume, and gives an overall reproduction and clearness that is the hall-mark of the good valve. The slope, 2.8 milliamps. per voit, with an impedance of 3,500, ensures perfect functioning.

These valves were found to give very fine tone and very powerful signals. There’ was a-clearness and trueness a — ar e 2 te

about the reproduction that indicated quite clearly the merit of their combination. For a 3-valve set a combination of DEH610, DHL610 and DEP610 was found to give excellent results. ‘ An account of the series of the new Osrams would not be complete without reference to the 2-volt vertical mounting sereen-grid valves. This type em-

bodies the latest results of research on the screen-grid, and gives excellent results. It was found to function best with about 60 volts on the screen and 150 on the plate. The filament requires 15 amperes at 2.volts, and, in common with other screen-grid valves of English make, it has the plate connected to the terminal at the top of the valve. Advice has been received that a super-power valve, which will take 250 yolts on the plate, is to arrive shortly, This valve should meet a long felt need for a power valve intermediate between the 171A type (DEP610) and the 210 type. This will be reviewed in the columns in due course. Ferranti "B" Power Pack, A: D. RILDY, LTD., has submitted to us for test a Ferranti H.T. Supply Unit which has recently made its ap pearance in New Zealand. The unit is encased in métal, the dimensions being approximately-a cubic foot. It is artistically finished’ in brown crystalline. The Ferranti unit is quite a departure from the usual conception of power units. Upon opening the lid, in which is 2 patent switch which immediately cuts off the power, there are seen nine wire-wound resistances which have taken the place of variable knobs. These resistunces are movable, and @

chart accompanies the power pack, giving instruétions as to which resistayite to use in numbered sockets forthe valves to be supplied. ; From these five tappings are taken through a battery cable to the set, thus providing for separdte voltage for the plates of the screen-grid, detector, L.F. and power valves, and the screening grid of the scréen-grid ‘valve. The unit is capable of delivering an output of 100 milliamps. at a voltage of 200. This is rather unusual, and fits it for use with sets using super-power valves and also for power amplifiers. Very : low voltages can be taken off for the . detector. ~ The cable connecting with the. mains is provided with three wires, oue

of which connects with the earthing system and ensures safety. Ferranti Meters. A very wide range of very accurate meters are now obtainable in this popular make. The portable models should appeal to the constructor or, operator who is interested in examin--ing his set. These are made with asmany as three different readings, milliamps, and two voltage scales. Resistances of 200 ohms. per volt in. ong type of meter, and 1,000 ohms. per viAt 1nanother ensure a very high gradé instrument. Meters reading up to 250 volts or as low as 7,6 dre obtainable Through judiciously combining external resistance a milliameter can he made to fulfil many purposés, and eoncerning this we shall devote an urticle at a future date. The meters are made in three distinct styles, panel mounting (flush and projecting) and portable,

Where vf flament volts ; jf,_ flament current Ri:, impedance X g amplifcation factor 9 va,, anode voltage; Vg , grid voltage:

sence erunaiemmemmenimaeremmeuelieammceainamaanineumarnaaas al Valves H1L210 HL610 S215 $625 DEL210 DBEL410 DBL610. DEH210 DEH410 DEH610 DBEP410 DEP610 P425 P625 P625A. DEP240 DEP215 DHP410 PT235 Hs HL8 Ps U5 TR Position vi. RF, 2.0 R.F. 6.0 8.G. _ 2.0 R.ES.G. 6.0 General 2.0 General 4.0 General 6.0 H.F, 2.0 HF. 4.0 B.F. 6.0 Power 4.0 L.F, Audio 6.0 Power 4.0 Power 6.0 Power 6.0 Power 2.0 Power 2.0: Power 4.0 Pen.. ° 2.0 A.O. 0.8 A.C, 0.8 A.C. ‘0.8 Ree. 5.0 Rec. 75 if. 0.1 01 0.15 0.25 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.25 0.25 vas. 150 150 Vz. 3.0 LB 170.0 100-150 max. Ri. g.. 23,000 20.0 30,000 80.0 200,000 Variable Max. Rect. Cur. 12,000 11.0 8,500 15.0 7,500 15.0 50,000 35.0 60,000 40.0 60,000 40.0 5,000 7.5 8,000 7.5 . 2,300 4.5 2,400 6.0 1,600 3.7 2,500 8.0 5,500 4.0 5,000 7.0 §5,000 * 90.0 55,000 40.0 17,000 17.0 6,000 6.0, 300 60 mil. 250 120 mil 150. 60 150 3.5 150 3.0 150 1.5 150 1.0 150 1.0 150 90 150 150 12.0 250 18.0 180 225 150 8.0 150 20.0. 160° 12,0 150 12.0 160 1.5 150 3.5 150 10.0 400-+-400 100-180 50-120 500-500 ‘Slope mA/V 0.87 1.0 0.85 0.92 -; 1.77 2.0 0.7 0.67 0.67 15 15 1.95 2.5 2.3 3 .o 16 LA 1.65 0.73. 10 1.0