4641 NXP
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Technical content
CAT. SHEET PHILIPS gy, Poh ig uw
7 SPECIAL VALVES
TRIODE FOR POWER AMPLIFIERS CHARACTERISTICS Heater voltage . . . . Vi = 4 v Heater current . 2. ik = 21 A Grid bias... 2 |. Vg = -140 v The following characteristics relate to a pair of valves in Class AB push-pull, with fixed grid-bias: Anode voltage . . . . Va = 1800 Vv Standing anode current . lao = 2X10 mA Anode current at peak Optimum load (anode to Maximum output. . . . Wo = 68 OW Total distortion . . . . dtot = 19° Vv iy Input required for full eee outputs ws = 105 Vims SPECIAL ADVANTAGES ir TEL Te | 1. Very low distortion Wveiil ah 2. High efficiency Ltt ih | ty Hl iii os DESCRIPTION HE i aS IE: IA - 7 The 4641 is a directly heated output Sat i sf 100 triode with a maximum anode dissipation UG acts ata 4: ee of 25 W; it has been designed especially = Fij/ii] in for amplifiers with class AB push-pull [214 | He output. The rated output is obtained only Hera ] qt 75 when fixed grid-bias is used. With an Fear ule al i| anode potential of 1500 V grid bias of = fff ial -144 V and 105 V (RMS) input to the grids, Ieee et He Hi the output power of a Class AB push-pull = FS eMail stage reaches 68 W, at only 1.9% total FFF) TAREE TT distortion. The anode current in the eset He ed absence of a signal is 10 mA per valve, FST npr tt | Hes rising to 41 mA per valve when the stage eireietea llUinier : is fully loaded; the optimum anode-to- | yf aT anode load is 40 k®. The same circuit, iii Sn Ali TELA but with 1000 V on the anodes and grid = “20 wl) 60 “0 “0 noe bias fixed at -93 V, provides an output of Anode current shown against grid bias 40 W at 2,35% total distortion, for an — foranode potentials of 1000 V and 1500V.
PHILIPS "MINIWATT” SPECIAL VALVES dot) Iai) wie Eye ye eae 4. prod Bald ESSEszecatisetrestn| eae OE PA eee enema | cesice tbe eee TT 0° SEETSTPES Pere SEHR ere SHEE SSEay ad faa assse cerca eceasscsietetectost ates Ne ( i ma eetee tua eit peezeestte = 5 my ee ee eae eee = fig giaoberaeran tates taae a ceaflseateneeduneeeeeiededutedecereteseesoeoaeee o oft FEET PT PEt peesrsestsust ress: 3 # * @ mi Bo Anode current Ia, required grid input Vi, (Velf = RMS) and total distortion dot. cs function of output power; for 2 valves in class AB push-pull with 1500 V on the anodes and fited grid bias. input of 65 V (RMS); in this case the optimum load is 20 kQ. When using automatic bias, maximum output will be less. With an anode voltage of 1000 V and a seli-bias resistance of 1700 2, in the lead between the mid-tap of the heater transformer and earth, the power developed across an anode-to-anode load of 3500 © is 29 W, the distortion amounting to 4,5%. The grid input required is 28 V (RMS) per valve, and the anode current varies between 25 and 28 mA. Owing to the high anode voltage, a special 4-pin base is used, and the internal layout of the valve has been designed to avoid risk of arcing. Max 68 a ft F] oo | g °° | 1 * | 1 A rangement of electrodes, | ~ connecti id maxim rt La Sinesstons ta muitmetes 4/45, K 833