Trade Jottings

Radio Record, Volume V, Issue 31, 12 February 1932, Page 23

Trade Jottings

"PE." Series of Valves

A NEW series of four-volt valves, the "PE" series, has been introduced by Philips. These feature such modern developments as the metal-clad principle of element screening and the inclusion of a variable-mu type "Selectode." An improved penthode with the advantage of high sensitivity is a further feature of the series. It should be realised that four-volt valves differ very materially from the 2.5 volt types, apart from their different filament rating, and while results from them are remarkable they must be handled with the knowledge of their peculiarities. Circuits are being evolved at the moment by Philips so that every advantage can be taken of the outstanding performance of which the new valves are capable when properly applied, and it must be understood that their applieation is necessarily more critical than the 2.5 volt types because of the increased efficiency which is possible, For example, the #452 Tis a metalclad type of screen-grid valve, the

slope of which reaches the unusual figure of 8 mA/V. Greater amplification is possible, and while the stability is enhanced by the metal-clad feature it must be intelligently used to secure the greater amplification of which it is capable. The metal-clad feature, which is common to both the £452 T screen-grid and £445 variable mu type "Selectode," enables efficient screening which eliminates the possibility of stray fields act‘ing on the elements. The inter-electrode capacity has thus been materially reduced permitting high gain and stable operation. For the’ benefit of readers we are listing herewith the characteristics of the valves comprising this new series, which includes the two metal-clad valves mentioned. together with the 4428, screen grid; 424, detector and amplifier; E443N, special penthode; E406, normal power type; and the 1561, full-wave rectifier.

Use Fil. Voltage Fil. Current Plate Voltage Screen Voltage Plate Current (m.2. ) Sereen Current m.2. Grid Bias (volts) Impedance (ohms) Mutual Conductance Amplification Factor 445 Y. Mu 4.0 1.4 200 160 1,75 2-40 259,000 300,000 1.2 300 H452L Se. Grid 4.0 11 200 100 3 5 2 3 1000 H442S H424 H443N 0406 Penthode Power 4.0 Det. Se. Grid Amp. 4.0 4.0 t 1.0 200 200 60 — 3 5.5 1 — $ 200.000 7,000 J 3.0 200 24 60 4.0 10 0=- «11.9 250 250 20 — 48 48 9 comet 39 24 22,000 1,000 2.7 6 1561 rw. Rect £0 \ A.C. Volts per PI. 506 Volts D.C. Output current 125 m.a,

Characteristics of the "P.E." Series