@oldhvymec, the old Hickok testers and the like tested
MUTUAL CONDUCTANCE
at low voltages, not at the operating voltages that they were likely to see. Makes a huge difference.
Would you pressure test a gas cylinder that routinely is filled with hydrogen at 2000 lbs by checking it with only 500lbs of pressure? Of course not, wouldn't even dream of it.
So why would you test a vacuum tube that runs at 450 VDC plate voltage with 100VDC or less. Sure, it can tell you that the tube is conducting but not how well it will conduct under a real load. That's best left to either testing in the actual amplifier or a modern tube tester like a Amplitrex AT1000 that can put up to 500VDC and 160 milliamps on the plates. There is another modern tube tester that sells in kit form that can test to much higher voltages as well. Both of these testers tie into a laptop computer and can plot curves for the tube under test. THAT's the kind of tester that can match tubes, not the older ones. Neither is cheap, I'd love to have one myself.
Not saying that the older tube testers are worthless by any means, they can be used for testing shorts (very important), gassy tubes and microphonics along with a doing life checks and basic health. But to match up tubes? NOT. That is best done either with one of the advanced testers or in the amplifier itself and a test meter. Anyone telling you different is either ignorant or trying to get over you. The best tube sellers today are using the latest test gear, the old TV7 type tube testers were the shitt years ago but old tech today. Times have changed my friend and this new tube testing technology is awesome.
BillWojo
Would you pressure test a gas cylinder that routinely is filled with hydrogen at 2000 lbs by checking it with only 500lbs of pressure? Of course not, wouldn't even dream of it.
So why would you test a vacuum tube that runs at 450 VDC plate voltage with 100VDC or less. Sure, it can tell you that the tube is conducting but not how well it will conduct under a real load. That's best left to either testing in the actual amplifier or a modern tube tester like a Amplitrex AT1000 that can put up to 500VDC and 160 milliamps on the plates. There is another modern tube tester that sells in kit form that can test to much higher voltages as well. Both of these testers tie into a laptop computer and can plot curves for the tube under test. THAT's the kind of tester that can match tubes, not the older ones. Neither is cheap, I'd love to have one myself.
Not saying that the older tube testers are worthless by any means, they can be used for testing shorts (very important), gassy tubes and microphonics along with a doing life checks and basic health. But to match up tubes? NOT. That is best done either with one of the advanced testers or in the amplifier itself and a test meter. Anyone telling you different is either ignorant or trying to get over you. The best tube sellers today are using the latest test gear, the old TV7 type tube testers were the shitt years ago but old tech today. Times have changed my friend and this new tube testing technology is awesome.
BillWojo
