<< 845 Vacuum Tube


Classification- Dome-type bulb of glass, filametary of carbennation Th-w a Copper ceramic base with four-prong bayonet golden pins, carbon plate triode.

Application -Audio power amplifier Class A1 or Class AB1.

Dimensions -Dimensions, outline diagrams of the tube and bases, and the arrangement of electrode connections to the base terminals are shown in Figures 1 and 2.
Fig 1
 
Fig 2
 

Nominal operating conditions and parameters
Filament voltage* ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 10V
Nominal filament current ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 3.2A
Plate voltage ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 1250V
Grid voltage** ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ -200V
Plate current ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 80mA
Plate resistance ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­1.7kohms
Amplification factor ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 5.0
Load resistance ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 3.4 kohms
Signal voltage(pk) ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ ˇ­69.0V
Output power ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 15W
Grid to plate transconductanceˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­3.0mA / V

*Alternating-current filament supply or Direct-current filament supply.
**Alternating-current filament supply is used. The grid and plate returns should be connected to a center tap on the secondary of the filament transformer.
Direct-current filament supply is used. The grid and platter returns are connected to the negative end of the filament.

Suggest Operating conditions and parameters
Class A1 power amplifier of single tube

Plate voltage
1000
1000
1250
V
Grid voltage
-145
-155
-209
V
Load resistance
6
9
16
kohms
Plate current
90
65
52
mA
Signal voltage(pk)
110
145
V
Plate resistance
1.7
1.9
2.1
kohms
Output power
24
21
24
W

Lass AB1 power amplifier of push-pull
Plate voltage
800
1000
1000
1250
V
Grid voltage
-125
-170
-175
-225
V
Load resistance
45
46
46
66
kohms
Plate current
80
70
40
40
mA
Signal voltage(pk)
177
240
V
Plate current (max. sig,)
177
240
V
Output power
40
75
75
75
W

Characteristics-Average characteristics
Figure 3. shown typical curves of plate currents of grid voltage for several values of plate voltages. It is alternating-current filament supply.

Fig 3

Limiting Operation Conditions for Safe Nor simultaneous ratings
Maximum plate voltage ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 1250 volts
Maximum plate dissipation ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 75 watts
Maximum plate current ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­120mA
Maximum input powe of signal ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ˇ­ 150 watts