The beam power tetrode KT88 has an anode limit dissipation power of 42W. In audio amplifier, when two electronic tubes are used as AB1 push-pull output, 100W power can be obtained, and KT88 can also be used in electronic voltage stabilizing circuit.
KT88 is similar to CV5220 and 6550 and can be used interchangeably.
Hot wire heating
UH………… 6.3 V
IH………… 1.6 A
Limit rating
------------- --KT94 KT100 KT94 KT100
Anode voltage.............................. 800 800 800 800 V
Second grid voltage......... 600 600 600 600 V
First grid voltage............ - 200 - 200 - 200 - 200 V
Dissipated power of anode............ 42 45 35 40 W
Second grid dissipation power...... 8 8 6 6 W
Dissipated power of anode plus second grid... 46 49 40 45 W
Cathode current.............................. 230 230 230 230 mA
Hot-wire cathode to cathode voltage......... 200 200 250 250 V
Glass shell temperature.............................. 250 250 250 250 C
First grid resistance
At self-bias
--- ---Pa + Pg2≤ 35W 0.47 MΩ
--- ---Pa +Pg2 > 35W 0.27 MΩ
At fixed bias
--- ---Pa +Pg2≤35W 0.22 MΩ
--- ---Pa +Pg2> 35W 0.10 MΩ
Interpole capacitance
------- Quadrode connection and triode connection
Input capacitance......... 16 --- 9.3 PF
Output capacitance......... 12 --- 17 PF
Cross-circuit capacitance......... 1.2 --- 7.9 PF
Static parameters
Tetrode connection
Ua…………………250V
Ug2……………… 250V
a………………… 140mA
Ig2(approx)…… 3mA
-Ug1(approx)……15V
Gm………………… 12mA/V
ri …………………12KΩ
μ g1-g2…………… 8
Triode connection
Ua.g2……………250V
Ia+g2……………143mA
-Ug1(approx)… 15V
Gm…………………12mA/V
ri…………………670Ω
μ………………… eight
Recommended working state (reference value)
Push and exchange AB1 amplification, triode connection (self-bias)
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 type AB1 amplifier, quadrupole connection (self-bias)
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
ū (g1-g1.pk) ………60 V
Push and exchange AB1 amplification superlinear connection (fixed bias)
（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-pull AB1 type amplification superlinear connection (self-bias)
(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
ū g1-g1.pk) …………… 104 71 V
Zout……………………… 4.8 4.5 kΩ
Push-pull type AB1 amplified tetrode connection (fixed bias)
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
ū g1-g1.pk) ……………… 67 V