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previous: Tailpiece I've got these strange tubes, 8417 ... -- 8/26/1999 3:59 AM

Re: Weird Tubes

8/26/1999 4:54 AM
Bruce	Re: Weird Tubes From Duncans site: http://duncanamps.simplenet.com/tubedata/search.mv?8417 I say they look more like a KT88 by that 100 watt rating for a pair in AB1! I have virtually no experience with them. When you say they test as new in your Sencore, I wonder what they test like in an circuit at full voltage. I find that if I run a 6v tube in the 4-5v filament range and hold the life test down, a good tube will just start to fall out of the "green" while a previously "tested good" tube will fall out very fast and maybe down into the bad area. New tubes seem to be able to sustain fairly solid emmisions when the cathode is a bit cold and weak ones are very sensitive to cathode heat. Of course there is no substitue for an in circuit test. Bruce

8/26/1999 4:54 AM

Bruce

Re: Weird Tubes

From Duncans site: http://duncanamps.simplenet.com/tubedata/search.mv?8417

I say they look more like a KT88 by that 100 watt rating for a pair in AB1!

I have virtually no experience with them.

When you say they test as new in your Sencore, I wonder what they test like in an circuit at full voltage.

I find that if I run a 6v tube in the 4-5v filament range and hold the life test down, a good tube will just start to fall out of the "green" while a previously "tested good" tube will fall out very fast and maybe down into the bad area.

New tubes seem to be able to sustain fairly solid emmisions when the cathode is a bit cold and weak ones are very sensitive to cathode heat.

Of course there is no substitue for an in circuit test.

Bruce