300B is directly-heated type cathode triode, used as class A1. In audio
amplifier it suits for the condition that the output power is 10W.
Heater
Uf(DC)………………5V
If(DC) …………… 1.2A
Maximum Rating
Ua……………480V
Pa………40W
Ik
with cathode bias………………100 mA
with fixed bias……………70 mA
Direct Interelectrode Capacitances
input……………9PF
output……………4.3PF
grid to plate……………15PF
Static parameter
Ua……………………300V
-Ug………………… 60V
Ia……………………60mA
Gm……………………5.5mA/V
ri……………………0.7 KΩ
u ……………………3.85
Pout…………………6.6W
typical workong parameter
aodio amplifier
class A1
Ua -Ug Ia RL Pout 2nd
V V mA Ω W db
200 42 30 2000 3 20
200 39 40 2500 2.6 26
250 55 30 2000 4.9 18
250 52 40 3000 4.0 26
250 50 50 2500 4.4 26
250 48 60 2000 4.7 26
250 48 60 2700 4.1 30
250 45 80 1500 5.0 26
300 65 40 2500 6.7 20
300 63 50 2000 7.2 21
300 63 50 3000 6.1 26
300 61 60 2400 6.6 26
300 58 80 1700 7.5 26
350 76 50 3600 7.8 26
350 74 60 2000 10.2 21
350 74 60 3000 8.3 26
350 74 60 4000 7.0 30
350 71 80 2200 9.6 26
400 91 40 5000 8.4 26
400 89 50 1000 11.5 21
400 89 50 4000 9.4 25
400 87 60 3500 10.5 26
400 84 80 2500 12.5 25
450 104 40 6000 9.5 26
450 102 50 5000 10.7
KT88-978
Recommended Operating Conditions(reference value)
Push-pull.classAB1.cathode bias.triode connection.
Ua.g2(b)………………400 485 V
Ua.g2(O)………………349 422 V
Ia+g2(0)………………2×76 2×94 mA
Ig+Ig2(max.sig)……2×80 2×101mA
RL(a-a)………………4 4 KΩ
-Ug(approx)………… 40 50 V
Pout………………… 17 31 W
Dtot ……………… 1.5 1.5 %
Pa.g2(0)…………… 2×26.5 2×40W
Pa.g2(max.sig)……２×19 2×27 W
Rk……………………2×525 2×525Ω
ū(g1-g1.pk)…… 78 114 V
Zout………………… 2 1.9 KΩ
Push-pull.classAB1.cathode bias.tetrode connection.
Ua(b)……………………560 V
Ua(0)……………………521 V
Ug2…………………… 300 V
Ia(o)……………………2×64 mA
Ia(max.sig)……………2×73 mA
Ig2(0)…………………2×1.7 mA
Ig2(max.sig)………… 2×9 mA
RL(a-a)……………… 9 kΩ
Rk……………………2×460 Ω
-Ug1(approx)…………30 V
Pout……………………50 W
Dtot……………………3 %
Pa(0) ………………2×33 W
Pa(max.sig) ………2×28 W
Pa2(0) ……………2×0.5 W
Pg2(max.sig) ……2×0.7 W
?(g1-g1.pk) ………60 V
KT100
Push-full.class AB1.fixed bias.ultra-linear connection.
(40%tapping points)
U a.g2(b)………………560 460 V
Ua.g2(0)………………553 453 V
Ia+g2(0)………………2ⅹ50 2ⅹ50mA
Ia+g2(max.sig)…… 2ⅹ157 2ⅹ140mA
RL(a-a)…………… 4.5 4 KΩ
-Ug1(approx)…… 75 59 V
Pout………………… 100 70 W
Dtot ………………………2 2 %
Pa+g2(0)………………2ⅹ27.5 2ⅹ27.5W
Pa+g2(max.sig)………2ⅹ33 2ⅹ27 W
ū(g1-g1.pk)…………140 114 V
Zout…………………… 7 6.5 KΩ
Push-full.class AB1.cathode bias.ultra-linear connection.
(40% tapping points)
Ua.g2(b) …………………500 375 V
Ua.g2(0) …………………436 328 V
Ia+g2(0) …………………2×87 2×87 mA
Ia+g2(max.sig) …………2×99 2×96 mA
RL(a-a) ………………… 6 5 kΩ
Rk…………………………2×600 2×400 Ω
-Ug1(approx) …………… 52 35 V
Pout…………………………50 30 W
Dtot……………………… 1.5 1.0 %
Pa+g2(0) ………………2×38 2×28.5 W
Pa+g2(max.sig) ……… 2×17 2×16 W
?(g1-g1.pk) …………… 104 71 V
Zout……………………… 4.8 4.5 kΩ
Push-full.class AB1.fixed bias.tetrode connection.
Ua(b) ………………………560 V
Ua(0) ………………………552 V
Ug2 ……………………… 300 V
Ia(0) ………………………2×60 mA
Ia(max.sig) ………………2×145 mA
Ig2(0) …………………… 2×1.7 mA
RL(a-a) …………………… 4.5 kΩ
-Ug1(approx) ………………34 V
Pout…………………………100 W
Dtot………………………… 2.5 %
Pa(0) ………………………2×33 W
Pa(max.sig) ………………2×28 W
Pg2(0) ……………………2×0.5 W
Pg2(max.sig) ……………2×4.5 W
?(g1-g1.pk) ……………… 67 V
