Subelement A: — Topic :
Question 6A178
Element 6 (Radiotelegraph)Given the following vacuum tube constants: Gp = 1000 V, Ip = 150 mA, Ig = 10 mA, Grid leaks = 5000ohms. What would be the grid bias voltage?
Explanation
In a vacuum tube circuit, the grid bias voltage can be developed by the flow of grid current (Ig) through a grid leak resistor. This is a common method, especially in transmitting tubes where the grid is driven positive on peaks, causing grid current to flow.
According to Ohm's Law, the voltage drop (V) across a resistor is the product of the current (I) flowing through it and its resistance (R): V = I * R.
In this case:
* Grid current (Ig) = 10 mA = 0.010 A
* Grid leak resistance = 5000 ohms
Calculating the grid bias voltage:
V = 0.010 A * 5000 ohms = 50 V
This 50 V drop creates a negative bias on the grid relative to the cathode, establishing the tube's operating point. Therefore, 50 V is the correct grid bias voltage.
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