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Old 25th May 2011, 10:10 PM   #1
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Default ECC88 - 6DJ8 Cascode Plate Curves

Does anyone have plate curves for the ECC88/6DJ8 in Cascode? Lots of mentions of doing this, but I can't seem to put my hands on the data.
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Old 26th May 2011, 09:52 AM   #2
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This any good? ECC88 @ The National Valve Museum
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Old 26th May 2011, 10:40 AM   #3
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Did this manually in my AVO maybe 20 years ago as I didn´t find the curves. Used Excel to get the curves. Can see if I still have them. If I remember it right I just used the Sg-voltage to bias the upper grid. Should be doable with any tubetester.
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Old 26th May 2011, 11:08 AM   #4
DF96 is offline DF96  England
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You can estimate from published curves.

Zeroth approximation:
Low triode works into a short circuit (vertical load line). Anode current merely goes through the upper triode - infinite Ra so curves are actually horizontal lines.

First approximation:
Low triode works into a load of 1/gm, so almost vertical load line. Upper triode sees lower triode as cathode degeneration resistor of Ra, so upper anode impedance is (mu+2)Ra. Curves are pentode-like.

Second approximation:
Remember that gm depends on current. This is when it gets messy.
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Old 26th May 2011, 02:17 PM   #5
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Not sure if it helps you any but the datasheets for some of my favorite "cheap alternates" have cascode curves... like the 6BK7 and 6BQ7:

http://www.mif.pg.gda.pl/homepages/f...93/6/6BK7B.pdf
http://www.mif.pg.gda.pl/homepages/f...93/6/6BQ7A.pdf

Pete
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Old 26th May 2011, 07:00 PM   #6
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Quote:
Originally Posted by pmillett View Post
Not sure if it helps you any but the datasheets for some of my favorite "cheap alternates" have cascode curves... like the 6BK7 and 6BQ7:
Great, that is helpful. Thanks.
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Old 27th May 2011, 05:21 AM   #7
cerrem is offline cerrem  United States
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I remember having the cascode curves for this tube somewhere...
I also remember the data sheets was written in Russian...so if you search the Russian tube makers website you might get lucky....

cerrem
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Old 27th May 2011, 09:22 PM   #8
Merlinb is offline Merlinb  United Kingdom
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ECC88 cascode curves with 50V on the upper grid.
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File Type: jpg ECC88.jpg (24.3 KB, 296 views)
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Old 1st June 2011, 05:15 PM   #9
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Is this what you need?

http://www.ianbell.ukfsn.org/pics/e88cc-phillips.pdf

Last page but one.

Cheers

Ian
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