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Old 10th June 2003, 08:14 AM   #1
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Default to-204(to-3) and to-247

in IR HEXFET with to-247 encapsulation , i think irfp044 and irfp040 is the best. but with to-3(to-204) encapsulation, which one is the best , irf240 or irf140?
why does nelson pass like to use to-3 encapsulation hexfet in his
commercial product ,for instance irf244.
is to-3 better than to-247 ? after i looked up datasheet of to-3 ,
i found to-3 is worse than to-247, pls tell me why,thanks.
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Old 10th June 2003, 08:25 AM   #2
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I think Nelson has used TO3 of history reasons. TO3 is more and more replaced by a more production friendly package. Don't use TO3 if you have a choice. I'm aware of that some people think that TO3 sounds better
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Old 10th June 2003, 09:00 AM   #3
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The only advantage of TO3 that I can think of right now is better humidity resistance
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Old 11th June 2003, 12:28 AM   #4
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Another possible reason for using a TO-3 is that most TO-3's have aTj of 200C as where plastic has a Tj of 150C. Thus, making the Power Derating slope of a TO-3 slightly better given equal power ratings. So, if you are cheap on heat sinking, or run your designs close, a TO-3 may give you a slightly better reliability. But, who runs their designs that close to maximum
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Old 11th June 2003, 03:00 AM   #5
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When I look at the hardware and the specs, it looks like the
TO-3 spec was created in more conservative times. I personally
prefer the hermetically sealed TO-3, with its higher mounting
surface area and more graceful response to high pressure
mounting over the plastic, but as the TO-3's are being closed out,
the choice is being made for us. I have about a 4 year supply,
and after that, it will be plastics for everything.
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Old 11th June 2003, 08:41 AM   #6
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Quote:
Originally posted by Nelson Pass
When I look at the hardware and the specs, it looks like the
TO-3 spec was created in more conservative times. I personally
prefer the hermetically sealed TO-3, with its higher mounting
surface area and more graceful response to high pressure
mounting over the plastic, but as the TO-3's are being closed out,
the choice is being made for us. I have about a 4 year supply,
and after that, it will be plastics for everything.
A 4 year supply? I thought that manufactures worked with the Just in Time principle .
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Old 11th June 2003, 06:54 PM   #7
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Right... A few years ago during the great mosfet shortage,
at least one of my competitors was forced to "rediscover"
the superiority of bipolar power transistors, followed by the
demise of the company as we knew it.

Last time I sat on a panel with Dan D., he publicly complained
that the TO-3 devices he uses are being discontinued (by
Motorola, probably reinventing itself as an internet company),
and I sympathise.

So I invest in quantities of devices that are not going out of style
soon, which gives me a better price, more quality uniformity,
constant supply, and a better negotiating position when buying
more.

So where do you buy your TO-3 transistors these days?
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Old 2nd September 2006, 06:37 AM   #8
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Default i can buy

Quote:
Originally posted by Nelson Pass
Right... A few years ago during the great mosfet shortage,
at least one of my competitors was forced to "rediscover"
the superiority of bipolar power transistors, followed by the
demise of the company as we knew it.

Last time I sat on a panel with Dan D., he publicly complained
that the TO-3 devices he uses are being discontinued (by
Motorola, probably reinventing itself as an internet company),
and I sympathise.

So I invest in quantities of devices that are not going out of style
soon, which gives me a better price, more quality uniformity,
constant supply, and a better negotiating position when buying
more.

So where do you buy your TO-3 transistors these days?
i can buy to-3 mosfet in china nation factory, but their product is very very expensive , i ask them why so much expensive, they said their product for military or aerospace , not for private.


or i can buy to-3 mosfet in chinese electronical market , but these mosfets are old or secondhand , i dont know real or fake.

i remember IR still produce to-3 mosfet , but for hi rel , maybe for military only, as what chinese nation factory does.
you still can buy to-3 mosfets from IR online .
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Old 2nd September 2006, 09:23 AM   #9
Magura is offline Magura  Denmark
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Default Re: i can buy

Quote:
Originally posted by john-china


i can buy to-3 mosfet in china nation factory, but their product is very very expensive , i ask them why so much expensive, they said their product for military or aerospace , not for private.

.

What brand are those chineese mosfets? Are they any good? How much is "much expensive" ?

Magura
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Old 2nd September 2006, 03:04 PM   #10
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Default Re: Re: i can buy

Quote:
Originally posted by Magura



What brand are those chineese mosfets? Are they any good? How much is "much expensive" ?

Magura

they produced any mosfet which IR is producing now , for instance irf240 ,irf230 , but they use WVM brand , for example, WVM12N50 , this mosfet is awarded by nation management office.
the price is $130 each piece at least. these mosfet can reach military standard which we call "7 special "standard in chinese,
it is very strict standard. if you buy their mosfets , they will give you some test files for these mosfets about "7 special" standard.

but i dont know if it is good or bad for audio , since i am a poor man.
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