different voltage measurements across EL34's

[EETStudent]

Do these voltages look too inconsistent to anyone?

G3 P G2 G1 Pin6 K
EL34(1) 0V 432 376 -30 92 0

EL34(2) 0V 424 372 -4 235 0

Mainly G1 and pin 6. I dont know enough about these elements or connections so they could be intended, but other voltage charts ive looked at have similar if not exact measurements between the two tubes.

[Enzo]

-4 on the grid looks all wrong. Pull the tube and measure it now. If it is still -4, then the amp has a problem, either a leaky coupling cap from the prior stage, or an open grid resistor. But if the bias voltage returns without the tube, then you have, as I would suspect, a bad tube.

Look at a tube data sheet to see what pin 6 does. Hint, it is not even there on many tubes. It is used normally as a convenient place to solder thnigs and is not a measure of what is going on inside the tube.

[EETStudent]

Enzo, I checked that grid voltage again, and like the other tube I got about 30VDC. And the heater voltages are about 30-31 as well, i suppose that is normal? Hence the 34 in the EL34? Where does the 6.3 heater volts come in? Is there a relation between the dual-triode heaters being in parallel(producing 6.3V) and the 6.3V from the pentode heaters?

[Enzo]

The E in EL34 means 6v heaters. the 34 is just the order in which the particular tube design was registered, there is no further meaning to the 34. Your tube runs on 6v heaters, measure from pin 2 to pin 7 of the socket. If you measure to ground from either pin it tells you if the heaters are elevated above ground, but the heater current flows thiough pins 2 and 7.

Please get used to including polarity on low voltage readings. We assume that 450 volts DC is positive, but we expect that the control grid voltage will be negative, so when you say it is 30v, that tends to mean +30 in the absence of the minus sign And if the heaters are at 30v, do you mean negative there as well? I hope not. I believe in +30 on the heaters and -30 on the grid though.

The relation between the preamp tubes and the power amp tubes all running on 6v is that they share a common heater voltage. It may be separate, but I would more likely expect the preamp tubes to elevate the heaters to 30vDC than the power tubes.