KT88S
Beam
Tetrode
The KT88S has an absolute maximum anode dissipation rating of 50W and is designed for use in
the output stage of an a.f. amplifier. Two tubes in Class AB1 give a continuous output of up to 120W.
The KT88 is also suitable for use as a series tube in a stabilised power supply.
HEATER
V
.................................................................................................................................................................................
h
6.3 V
Ih (approx.) ..........................................................................................1.6 A
MAXIMUM RATINGS
Absolute and Design Maximum
a
.....................................................................................................................................................................
V
V
...................................................................................................................................................................
g2
V
................................................................................................................................................................
a,g2
-V
.................................................................................................................................................................
g1
p
......................................................................................................................................................................
a
p
....................................................................................................................................................................
g2
p
................................................................................................................................................................
a+g2
I
........................................................................................................................................................................
k
V
..................................................................................................................................................................
h-k
T
.................................................................................................................................................................
bulb
R
(cathode bias)
g1-k
p
<40W .................................................................................. 470 kΩ
a+g2
p
>40W .................................................................................. 270 kΩ
a+g2
800 V
600 V
600 V
200 V
50 W
8W
59 W
230 mA
250 V
250
Rg1-k (fixed bias)
p
<40W .................................................................................. 220 kΩ
a+g2
p
>40W .................................................................................. 100 kΩ
a+g2
o
C
(Revised 3/1/96)
P E N T A L A B O R A T O R I E S
9740 COZYCROFT AV. * CHATSWORTH * CALIFORNIA 91311
(800) 421-4219 * (818) 882-3872 * FAX: (818) 882-3968
ELECTRON TUBES FOR INDUSTRY
-
KT88S BEAM TETRODE
CAPACITANCES (measured on a cold unscreened tube)
Triode Connection
C
C
C
...................................................................................................................................................................... 7.9 pF
g1-a,g2
g1-all less a,g2
a,g2-all less g1
..........................................................................................................................................................
..........................................................................................................................................................
9.3 pF
17 pF
Tetrode Connection
C
........................................................................................................................................................................... 1.2 pF
g1-a
C
g1-all less a
C
a-all less g1
...............................................................................................................................................................
...............................................................................................................................................................
16 pF
12 pF
CHARACTERISTICS
Triode Connection
V
............................................................................................................................................................................
a,g2
I
..............................................................................................................................................................................
a+g2
-Vg1
(approx.)
g
................................................................................................................................................................................
m
r
...................................................................................................................................................................................
a
.............................................................................................................................................................
250 V
143 mA
15 V
12 mmho
670 Ω
µ.................................................................................................................... 8
Tetrode Connection
V
.................................................................................................................................................................................
a
V
...............................................................................................................................................................................
g2
I
....................................................................................................................................................................................
a
Ig2
-Vg1
g
m
r
...................................................................................................................................................................................
a
µ
g1-g2
..................................................................................................................................................................
(approx.)
(approx.)
................................................................................................................................................................................
.............................................................................................................................................................
...........................................................................................................................................................................
TYPICAL OPERATION
Push-Pull. Class Ab1, Cathode Bias, Tetrode Connection
V
.............................................................................................................................................................................
a(b)
V
.............................................................................................................................................................................
a(o)
V
...............................................................................................................................................................................
g2
I
................................................................................................................................................................................
a(o)
I
a (max signal)
I
g2(o)
I
g2 (max signal)
R
L(a-a)
*R
...............................................................................................................................................................................
k
-V
g1 (approx.)
P
out
D
tot
...............................................................................................................................................................
..............................................................................................................................................................................
.............................................................................................................................................................
..........................................................................................................................................................................
..............................................................................................................................................................
..............................................................................................................................................................................
..............................................................................................................................................................................
250 V
250 V
140 mA
3mA
15 V
11.5 mmho
12 kΩ
8
560 V
521 V
300 V
2 x 64 mA
2 x 73 mA
2 x 1.7 mA
2 x 9 mA
9kΩ
2 x 460 Ω
30 V
50 W
3%
Page 2
KT88S BEAM TETRODE
**I.M. .................................................................................................. 11 %
p
.............................................................................................................................................................................
a(o)
p
a (max signal)
p
g2 (o)
p
g2 (max signal)
V
(g1-g1)(ac) crest
.............................................................................................................................................................
..........................................................................................................................................................................
...........................................................................................................................................................
........................................................................................................................................................ 60 V
* It is essential to use two seperate cathode bias resistors.
** Intermodulation distortion; measured using two input signals at 50 and 6000 Hz (ratio of amplitude 4:1)
Push-Pull. Class AB1, Fixed Bias, Tetrode Connection
2 x 33 W
2 x 12 W
2 x 0.5 W
2 x 2.7 W
V
.............................................................................................................................................................................
a(b)
V
.............................................................................................................................................................................
a(o)
V
...............................................................................................................................................................................
g2
I
................................................................................................................................................................................
a(o)
I
a (max signal)
I
g2(o)
I
g2 (max signal)
R
L(a-a)
*-
Vg1 (approx.)
P
out
D
tot
...............................................................................................................................................................
..............................................................................................................................................................................
.............................................................................................................................................................
..........................................................................................................................................................................
.............................................................................................................................................................
..............................................................................................................................................................................
..............................................................................................................................................................................
560 V
552 V
300 V
2 x 60 mA
2 x 145 mA
2 x 1.7 mA
2 x 15 mA
4.5 kΩ
34 V
100 W
2.5 %
**I.M. .................................................................................................. 10 %
p
.............................................................................................................................................................................
a(o)
p
a (max signal)
p
g2 (o)
p
g2 (max signal)
V
(g1-g1)(ac) crest
.............................................................................................................................................................
..........................................................................................................................................................................
...........................................................................................................................................................
........................................................................................................................................................
2 x 33 W
2 x 28 W
2 x 0.5 W
2 x 4.5 W
67 V
* It is essential to provide two seperately adjustable bias bias voltage sources, having a voltage adjustment range of +/- 25%
** Intermodulation distortion; measured using two input signals at 50 and 6000 Hz (ratio of amplitude 4:1)
Push-Pull. Class AB1, Cathode Bias, Ultra-Linear Connection (40% Tapping Points)
V
V
I
I
R
*R
-V
...................................................................................................................................
a,g2(b)
...................................................................................................................................
a,g2(o)
.....................................................................................................................................
a+g2(o)
a+g2(max signal)
L (a-a)
..........................................................................................................................................
k
g1 (approx.)
......................................................................................................................
...................................................................................................................................
.........................................................................................................................
500 375 V
436 328 V
2 x 87 2 x 87 mA
2 x 99 2 x 96 mA
65kΩ
2 x 600 2 x 400 Ω
52 35 V
Page 3
KT88S BEAM TETRODE
P
.........................................................................................................................................
out
.........................................................................................................................................
D
tot
50 30 W
1.5 1 %
**I.M. ............................................................................ 4 3 %
p
p
V
Z
...................................................................................................................................
a+g2(o)
a+g2(max signal)
(g1-g1)(ac)crest
..........................................................................................................................................
out
...................................................................................................................
....................................................................................................................
2 x 38 2 x 28.5 W
2 x 17 2 x 16 W
104 71 V
4.8 4.5 kΩ
* It is essential to use two seperate cathode bias resistors.
** Intermodulation distortion; measured using two input signals at 50 and 6000 Hz (ratio of amplitudes 4:1)
Push-Pull. Class AB1, Fixed Bias, Ultra-Linear Connection (40% Tapping Points)
V
V
I
I
R
*-V
P
D
...................................................................................................................................
a,g2(b)
...................................................................................................................................
a,g2(o)
.....................................................................................................................................
a+g2(o)
a+g2(max signal)
L (a-a)
g1 (approx.)
.........................................................................................................................................
out
.........................................................................................................................................
tot
......................................................................................................................
...................................................................................................................................
......................................................................................................................
560 460 V
553 453 V
2 x 50 2 x 50 mA
2 x 157 2 x 140 mA
4.5 4 kΩ
75 59 V
100 70 W
22%
**I.M. ............................................................................ 11 10 %
p
p
V
Z
...................................................................................................................................
a+g2(o)
a+g2(max signal)
(g1-g1)(ac)crest
..........................................................................................................................................
out
...................................................................................................................
....................................................................................................................
2 x 27.5 2 x 22.5 W
2 x 33 2 x 27 W
140 114 V
7 6.5 kΩ
* It is essential to provide two seperately adjustable bias bias voltage sources, having a voltage adjustment range of +/- 25%
** Intermodulation distortion; measured using two input signals at 50 and 6000 Hz (ratio of amplitude 4:1)
Push-Pull. Class AB1, Cathode Bias, Triode Connection
V
V
I
I
R
-V
P
D
...................................................................................................................................
a,g2(b)
...................................................................................................................................
a,g2(o)
.....................................................................................................................................
a+g2(o)
a+g2(max signal)
L (a-a)
g1 (approx.)
.........................................................................................................................................
out
.........................................................................................................................................
tot
......................................................................................................................
...................................................................................................................................
.........................................................................................................................
400 485 V
349 422 V
2 x 76 2 x 94 mA
2 x 80 2 x 101 mA
44kΩ
40 50 V
17 31 W
1.5 1.5 %
*I.M. ............................................................................. 5.6 5.6 %
p
p
...................................................................................................................................
a+g2(o)
a+g2(max signal)
...................................................................................................................
2 x 26.5 2 x 40 W
2 x 19 2 x 27 W
Page 4
KT88S BEAM TETRODE
R
............................................................................................................................................
k
V(
g1-g1)(ac)crest
..........................................................................................................................................
Z
out
....................................................................................................................
2 x 525 2 x 525 Ohms
78 114 V
2 1.9 kΩ
* Intermodulation distortion; measured using two input signals at 50 and 6000 Hz (ratio of amplitude 4:1)
INSTALLATION
The tube may be mounted either vertically or horizontally.
When the tubes are mounted vertically, it is recommended that the centers of the tube sockets are
not less than 4 inches apart and that pins 4 and 8 of each tube are in line.
When the tubes are mounted horizintally, it is recommended that the centers of the tube sockets
are not less than 4 inches apart and that pins 4 and 8 of each tube are in the same vertical line.
One tube should not be mounted directly above another.
Free air circulation around the tube is desirable.
Base: Metal shell, wafer octal
Pin:
1. N.C.
2. h
3. a
4. g2
5. g1
6. N.C.
7. h
8. k,bp
Page 5
Loading...