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KT33C

Sensibly equivalent to:
CV1503 VR503
See also:
Osram KT2, KT76, KT33C, KT66, KT61, KT66, PX4 & PX25 Advert
    
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The KT33C audio power output valve was introduced in 1939 and replaced the KT33. This version had a heater centre tap.
For the 5 Watts output the anode load would be 3,000 Ohms. The distortion at full power is 7.5%.
The mutual conductance is given as 10, this suggests a very small gap between the cathode and the control grid, in turn implying very tight manufacturing tolerances.
The classic envelope is 42 mm in diameter and, excluding the IO base pins, is 100 mm tall.
References: Datasheet & 1043. Type KT33C was first introduced in 1939.

 

Pin Connections
IO
1
2
3
4
5
6
7
8
hct
h
a
g2
g1
-
h
k

 

Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
Pout
26
0.3
200
200
-13.2
60
10
10.0
5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated May 19, 2014.
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