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In Reply to: Re: Great post Andy.... posted by andy evans on March 9, 2007 at 15:02:34:
Andy:I too liked your posts. Studied it and looked up a few tubes. Happy too that NJ7P tube database is back after a few days of hinky operation.
You mention 6J6G. I know the 6J6 to be an IDHT twin triode.
Do you mean 1J6G. I have been looking high and low for information on Class A operation of 1J6G. I finally bought some and tested on my RAT tube tester. However, I got a mu of 2- - 21. Now maybe I tested wrong -- you indicate a mu of 14, assuming you are talking 1J6. Do you have a data sheet on it?
Follow Ups:
However, I got a mu of 2- - 21
Sorry. Left hand broken - bad for typing.I meant 20 to 21. I have a Steve Bench design RAT tube tester I built three years ago. However, I did not build his supplemental power supply for DHTs, so the ony DHT I have tested was 1J6. I calibrated first with known IDHT tubes, but my mu readings were stable and consistent.
Anyway, my starting point was a search of the (now) many good web sources for datasheets to find some Class A info on 1j6, but to no avail.
This page links to a number of data sheets, but I didn't see any with class A.
Indeed - all the online data looks like class B. I don't know where I got mu of 14 from. Kurt Strain was using them - maybe something he wrote? Sounds about right, though. It's a smooth sound, but not holographic like the best DHTs.
"I don't know where I got mu of 14 from."I don't know for sure anymore, but 14 sounds about right to me, too. These are nice sounding, but a bit warm and fuzzy for a DHT, after looking into other DHT's out there. Very easy filament to heat, though, not a lot of current. They were designed for battery operated class B output stages drawing low power.
because he used 1J6s as Class A drivers. I studied a lot of his posts, but never saw a statement of mu for Class A purposes. I never asked him, concluding instead to procure and test. Have not tried them in a circuit yet.
I built a PP KT-88 amp using 1J6G as input and driver. Mu is indeed *about* 14, but it' hard to be accurate as there's no class-A data about. I just extrapolated the class-B data.
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