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Old 17th January 2007, 03:18 PM   #11
nhuwar is offline nhuwar  United States
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I was thinking parafeed just to keep the power going through the transformer down.

I was just thinking of reducing the dissipation of dc current in the primary thats all.

Nick
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Old 17th January 2007, 04:47 PM   #12
kevinkr is offline kevinkr  United States
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Not a bad thought, but how wedded are you to using these particular tubes? And at these power levels? I know that they are cool looking, and high power is also appealing, but it seems like a herculean design task to get something together that will be reliable, sound good, and not take the entire contents of the Fort Knox vault to build..

How much power do you really need? What kind of speakers are you using and how much space do you have to fill? Perhaps even more importantly do you have major $$$$ to devote to opt development as it is unlikely that the first protos will be acceptable?

A friend of mine designed and developed a c core based opt for an 845 SE amplifier he was designing, it took him three attempts to get a transformer he could live with.. Design target was 10K, L >100H, 100mA, 3KV insulation system, and a first resonance above 50kHz - what he ended up with was good, but he didn't quite make his bandwidth requirement. I don't remember his leakage inductance target, but I do remember he did not attain it, nor the stray capacitance either. This fellow was doggedly determined and the end result was probably about as good as you can get. He told me afterwards that he would think long and hard before he ever attempted to wind another large opt..
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Old 17th January 2007, 04:53 PM   #13
nhuwar is offline nhuwar  United States
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I can't help it. I've always done thing abit overboard!
Besides it keeps me busy and I dont mind spending a few grand and devoting a year or two to make it right.

Nick
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Old 17th January 2007, 05:03 PM   #14
kevinkr is offline kevinkr  United States
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Well that's pretty cool. As long as you know what you are up against.. I'm the old naysayer..

I'd be happy to review design choices with you when the time comes.
Quincy isn't that big a place..

K
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Old 17th January 2007, 05:13 PM   #15
nhuwar is offline nhuwar  United States
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Well Im working on a schematic right now but the problem is I have yet to get curve captor to work.
Once that is done It should go alot faster. Becasue you that 813 is a common everyday tube


But I'm making a basic schematic the old fashion way with a pencial and when it's done I will post it.

Nick
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Old 17th January 2007, 05:23 PM   #16
kevinkr is offline kevinkr  United States
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Hi Nick,
Download LTspice if you haven't done so already - you can use it to make your schematics.

Curve Captor incidentally will only work with triodes and diodes, there is no option for pentodes or tetrodes. Not a problem of course if you triode connect the 813 in which case CC makes very good models.

Paintcc has a sub program known as paint_kip that is for pentodes, but it doesn't seem capable of making very accurate captures. I have had limited success.
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Old 17th January 2007, 05:46 PM   #17
nhuwar is offline nhuwar  United States
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I have already downloaded ltspice but there is no tubes in it so it's kind of useless to me at the moment.
The program seams very limited in the components it has in it's library.

Nick
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Old 17th January 2007, 05:55 PM   #18
rdf is offline rdf  Canada
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http://www.duncanamps.com/spicevalves.html
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Old 17th January 2007, 06:09 PM   #19
nhuwar is offline nhuwar  United States
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There not for ltspice and besides there's no 813 on the list i've checked.
Any other ideas.

Nick
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Old 17th January 2007, 06:20 PM   #20
rdf is offline rdf  Canada
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Almost all of the non-3f4 models work with LTspice and I'm not aware of an 813 model.
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