Finally reading the RCA receiving tube manual from the 50s and came across the statement about the benefit of tetrodes being that there is little relationship between plate voltage and plate current. I want to make sure I am understanding plate loads and the creation of signal correctly.
A tube amplifier stage has a set DC voltage on the plate, coming through a load resistor off the B plus line. With no current, both sides of the resistor should show the same voltage. When constant current flows through the tube, a constant voltage drop appears across the resistor because IR=V. By changing plate current, the resistive load of the plate resistor (say 100k) produces a voltage swing to match, which becomes our signal output for the stage.
Now take for instance two differential amplifier stages in a row. If the plate resistor of V1 produces a voltage signal, we can tap that through a capacitor and apply it to a second stage as an input signal. Doesn't the grid leak resistor of the second stage also present a load to the first stage in addition to Rpk? How do the two load resistors interact since they're both loads but not in parallel?
If we connect a capacitor from V1 plate to ground (parallel to a V2 grid leak) I believe that would result in zero voltage swing on V1 plate, but does it also load the tube and drag down B+ as the tube tries to supply more current into an AC short, or does it return us back to the case where there is only Rpk with no current flowing because there is no longer a voltage swing and therefore no plate current?
I've had volume controls change the signal coming off of the plate as you turn them past a certain point, is this dual load why?
A tube amplifier stage has a set DC voltage on the plate, coming through a load resistor off the B plus line. With no current, both sides of the resistor should show the same voltage. When constant current flows through the tube, a constant voltage drop appears across the resistor because IR=V. By changing plate current, the resistive load of the plate resistor (say 100k) produces a voltage swing to match, which becomes our signal output for the stage.
Now take for instance two differential amplifier stages in a row. If the plate resistor of V1 produces a voltage signal, we can tap that through a capacitor and apply it to a second stage as an input signal. Doesn't the grid leak resistor of the second stage also present a load to the first stage in addition to Rpk? How do the two load resistors interact since they're both loads but not in parallel?
If we connect a capacitor from V1 plate to ground (parallel to a V2 grid leak) I believe that would result in zero voltage swing on V1 plate, but does it also load the tube and drag down B+ as the tube tries to supply more current into an AC short, or does it return us back to the case where there is only Rpk with no current flowing because there is no longer a voltage swing and therefore no plate current?
I've had volume controls change the signal coming off of the plate as you turn them past a certain point, is this dual load why?
