Tube amp question

While I agree with you that a tester that cannot properly test a KT150- shows the limits of the tester, ( BTW, yours- nor any Hickok- I am aware of can test these tubes--and your KT88 spec is no good for them) it also points to the fact that they need more voltage than 400 volts to come to spec, IMHO.

I don't think the Hickok subjects tubes to full operating voltages. There is no B+ voltage adjustment for that purpose. It seems that you have to explain why 400V is specified as an operating point for that tube when in class A mode.

@falconquest Plate voltage is the voltage on the tube from cathode (usually at or near ground) to the plate of the tube. The plate is exactly what it sounds like; it receives electrons that flow from the cathode. The audio signal is imposed by the grid (another element of the tube) over the much larger electron flow from cathode to plate; in this way it can amplify.

@daveyf If it were me I'd be testing a KT150 as a KT88 since our tester is an older Hickok. I would also not be surprised to find that a KT150 might not test properly under those circumstances.

That does not mean that the tube does not work at 400V. It simply points at a limitation in the tester.

KT150's require 600 volts at the plate.

@daveyf @falconquest This statement is false. If you look at the tube's specs

you'll see that for class A operation (single tube) 400V is recommended. This would be the most current you would want to run on the tube for nominal lifespan. When running 500V you would run less current and even less if running at 600V.

IOW the class of operation is playing a role. If in class A when the tube is always conducting you don't want to run as much plate voltage if you want the tube to be reliable.

Contact Black Ice for the recommended bias point when installing this tube in their amp.