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In Reply to: RE: 12C42C posted by Banat on April 12, 2015 at 09:51:54
What about Rp and max plate dissipation?
In other words, is this a good tube for OTL?
It looks like a 6C33C as seen in a fun-house mirror.
Follow Ups:
Hi Lew !
From my modest information basic parameters for 12C42C tube is :
- Filament = 12,6V / 4,9A (+/- 0,4A)
- Pd const. max = 120W ( at Vp=120V & Ip=1A +/- 0,2A )
- Rp min = 65R
- special 9 pin jumbo magnoval ceramic socket .
Yes is look interesting , but basically 12C42C tube consist from about three section similar or smaller of 6C33C tube , arranged in 120 degree schedule and internal electrically connected in parallel .
No practical proof but I believe it is good tube for OTL .
__
"Art which does not have the appearance of art is true art."
- Old Roman saying -
Edits: 04/14/15
If those numbers are real (and I cannot read the Russian, only your English), and if the specs are really valid and not exaggeration, then this tube rivals the 7241. Pretty cool, if you can get a bunch.
LewNo exaggeration of specs here , those specs & graphs are original from Ulyanovsk tube factory , well known for quality production of their variant of 6c33c-b power triodes and other pass regulator power triodes .
Any way what`s concern me is the real life test of those pretty old NOS 12C42C tubes , as tubes long term durability , Ik-max peak potential , tube cooling issues , and other specific tube characteristics important for OTL application .
__
"Art which does not have the appearance of art is true art."
- Old Roman saying -
Edits: 04/14/15
To that concern, Ralph advocates running the power tubes (only) on filaments only for up to several days prior to application of B+. I have read elsewhere of the putative benefits of "baking" old power tubes at very low temperature (e.g., as low as 120 degrees F to 200 degrees F) for a day or so. I've never tried that, but I did run the heaters of my 6C33Cs and later the 7241s as per Ralph's advice. I don't quite understand the rationale, but my 7241s have now been in use for nearly two years with absolutely no drift in bias setting. I've no proof that burning in the filaments and the apparent long term stability of the tubes are related, of course.
Lew
Many thanks for that information ! ,since I`m sure that Ralph know very well reasons why all those NOS low Rp power triodes need several days of filament&cathodes activation before B+ is applied .
And yes I read somewhere long time ago about `` baking`` of tubes , I think that praxis main intention is to reactivate tube getter , improving internal level of vacuum , but admit that I never try that .
BTW ,
just comparing , one advantage of 7241 tube over 12C42C tube is that 7241 have three separate cathode pins ,one separate cathode contact pin for each separate cathode , which allow application of three external ballast resistors for better mutual dynamic current share between three tube sections , 12C42C tube don`t have that possibility .
__
"Art which does not have the appearance of art is true art."
- Old Roman saying -
To me -- tubes are works of sonic and visual art.
Vbr,
Sam
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