Bias Settings For Safe Plate Dissipation - Class AB 70%    Class A 90%
Explain This
Class   
Tube Type    
Plate Voltage    
     mA


Calculate Plate Dissipation Based On Plate Voltage And Cathode Current Readings.
In these calculations, 5% of the cathode current is assumed to be screen current. This calculator is for a single tube.

Plate voltage
DC voltage measured between plate and cathode. (Actual Plate Voltage)
Example:
Octal - pins 3 and 8
9 pin - pins 7 and 3

Cathode Current (milliamps)
Displays Approximate Plate Current After Calculation

Plate Dissipation (Watts)
Note: For calculating plate dissipation in cathode biased circuits, subtract the measured cathode voltage from the measured plate voltage and use that as the plate voltage in the calculator above.
Calculate Plate Dissipation In Cathode Biased Output Stage Based On Voltage And Resistance Readings
In these calculations, 5% of the cathode current is assumed to be screen current. With multiple tubes sharing the same cathode resistor, this calculator assumes the tubes are fairly well matched.

How many tubes share the same cathode resistor? (typically 1 to 4)

Voltage measured across cathode resistor

Actual resistance of cathode resistor

DC voltage measured between plate and cathode. (Actual Plate Voltage)
Example:
Octal - pins 3 and 8
9 pin - pins 7 and 3

Plate dissipation per tube (Watts)

Approximate plate current in each tube (in milliamps)





Will calculate and display plate power dissipation and approximate plate current per tube.
Jim Jones' Bias Tables
Click here to vist the "House of Jim" Website


EL84/6V6GT - 12W
Hot (70%)
Avg (60%)
Cool (50%)
200V
42mA
36mA
30mA
225V
37mA
32mA
27mA
250V
34mA
29mA
24mA
275V
31mA
26mA
22mA
300V
28mA
24mA
20mA
325V
26mA
22mA
18mA
350V
24mA
21mA
17mA
375V
22mA
19mA
16mA
400V
21mA
18mA
15mA

 


 

7189A - 13.2W
Hot (70%)
Avg (60%)
Cool (50%)
200V
46mA
39mA
33mA
225V
41mA
35mA
29mA
250V
37mA
32mA
26mA
275V
34mA
29mA
24mA
300V
31mA
26mA
22mA
325V
28mA
24mA
20mA
350V
26mA
23mA
19mA
375V
25mA
21mA
18mA
400V
23mA
20mA
17mA

 


 

EL34 - 25W
Hot (70%)
Avg (60%)
Cool (50%)
300V
58mA
50mA
42mA
325V
54mA
46mA
38mA
350V
50mA
43mA
36mA
375V
47mA
40mA
33mA
400V
44mA
38mA
31mA
425V
41mA
35mA
29mA
450V
39mA
33mA
28mA
475V
37mA
32mA
26mA
500V
35mA
30mA
25mA

 


 

6L6GC - 30W
Hot (70%)
Avg (60%)
Cool (50%)
300V
70mA
60mA
50mA
325V
65mA
55mA
46mA
350V
60mA
51mA
43mA
375V
56mA
48mA
40mA
400V
53mA
45mA
38mA
425V
49mA
42mA
35mA
450V
47mA
40mA
33mA
475V
44mA
38mA
32mA
500V
42mA
36mA
30mA

 


 

6550 - 35W
Hot (70%)
Avg (60%)
Cool (50%)
400V
61mA
53mA
44mA
425V
58mA
49mA
41mA
450V
54mA
47mA
39mA
475V
52mA
44mA
37mA
500V
49mA
42mA
35mA
525V
47mA
40mA
33mA
550V
45mA
38mA
32mA
575V
43mA
37mA
30mA
600V
41mA
35mA
29mA

 


 

 

 







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