From roo–(at)–enry.henry.net Sun Aug 20 09:53:31 CDT 1995
Article: 126 of rec.audio.tubes
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From: roo–(at)–enry.henry.net (root)
Newsgroups: rec.audio.tubes
Subject: Re: 12AT7 vs. 12AX7?
Date: 20 Aug 1995 03:25:32 GMT
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Wilhelm Reich (wilhel–(at)–akima.wustl.edu) wrote:
: Whadda you know about these things?
i have the operational specs for both from my copy of (ta-da!) the 1959
ARRL handbook 😎
Well, I’ve changed the format from a table going across to one going
down so I don’t have to worry about 80 columns restriction on all this data
8-). Since this is like 10 or 20 pages FINE print, I’m only putting data on
those 2 tubes 8-).
Type 12AT7 : 12AX7
:
Name High-u dual triode (10): High-u Dual Triode
:A1 Amp.(10) : Class B
Base 9A : 9A
Fil or Header:
V.12.6 : 6.3 : 12.6: 6.3
Amp. 0.15 : 0.3 : 0.15: 0.3
Capacitances uuf : :
C(in) 2.2 (7) : 2.2 (8) : 1.6 (7) : 1.8 (8)
C(out) 0.5 (7) : 0.4 (8) : 0.46(7) : 0.34 (8)
C(gp) 1.5 (7) : 1.5 (8) : 1.7 (7) : 1.8 (8)
Plate Suplly V. 100 : 250 : 250 : 300
Grid Bias 270 (*) : 200 (*) : -2 : 0
Screen Volts ——–:——– : ————:———–
Screen Ma.——–:——– : ————:———–
Plate Ma. 3.7 : 10 : 1.2 : 40 (2)
Plate Res. Ohms 15K : 10.9K : 62.5K :———–
Transconductance(11) 4000 : 5500: 1600:———–
Amp. Factor(4) 60 : 60 : 100 : 14 (5)
Load Res. Ohms ——–:——– : ————: 16K(6)
Watts Output ——–:——– : ————: 7.5

(*) Cathode resistor ohms
(1) Per Plate
(2) Maximum-signal current for full-power output.
(4) Unless otherwise noted.
(5) No signal plate ma.
(6) Effective plate-to-plate.
(7) Triode No. 1.
(8) Triode No. 2.
(10) Values for each section.
(11) Microohms.