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Old 11th November 2008, 10:16 PM   #551
hayenc is offline hayenc  United States
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Quote:
Originally posted by carpenter
I think I just got lucky:

I was rummaging through my pcb collection and ran across a pair of BrianGT Aleph boards.

I'm comparing schematics (Aleph 3 and Aleph J) and they seem similar except for values, transistors, and transistor footprints.

Looks like I've got some reading to catch up on--unless Nelson's planning a quick turn around on his pcbs. Just in case, I've got a little bitty kitty hidden under the house...



Hummmm.

I agree. The BrianGT boards look like they will work for this. I did an Aleph 2 and used an extra set of the external FET boards for the 2, so I have a spare set for the single FET version. Worth trying with some matched 250's I have and will see how it turns out.
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Old 11th November 2008, 10:37 PM   #552
Variac is offline Variac  United States
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To clarify further, the boards are Aleph X 1.0 so they are X'ed already, but Zenny is gonna help AR2 (and apparently a 100 other guys and their brothers - including me and my brother!) change the inputs to JFETS, the "latest thing" by slightly changing the boards. It shouldn't be a bunch of changes..

As I mentioned elsewhere, Nelson told me that the IRFP250's are just a TO-3 can with 2 IRFP 240 dies inside. Clearly you can use 240's but you need twice as many ( my math skills- amazing! ) Apparently they are pretty pricey these days, as I believe that they are no longer made. If you can't use TO-3 format you don't want IRFP250's


A major factor driving this is that a bunch of us got lovely and huge amp chassis' with heatsinks and power supplies donated by Nelson at the Burning Amp Festival. It is a bit more complicated because the chassis came with 240's and 9240's installed for a pushpull setup. But we also got pocketsful of IRFP250 MOSFETS so why not use them?
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Old 11th November 2008, 11:17 PM   #553
Magura is offline Magura  Denmark
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Quote:
Originally posted by Variac

As I mentioned elsewhere, Nelson told me that the IRFP250's are just a TO-3 can with 2 IRFP 240 dies inside. Clearly you can use 240's but you need twice as many ( my math skills- amazing! ) Apparently they are pretty pricey these days, as I believe that they are no longer made. If you can't use TO-3 format you don't want IRFP250's

But we also got pocketsful of IRFP250 MOSFETS so why not use them?

There seems to be some confusion about those TO-3 can parts.

The TO-3 can parts are IRF250, the IRFP240 and 250 are of the TO-247 package variety.

It's not all that complicated, as the parts that comes in both flavors, are named IRF-XXX for the TO-3 package, and IRFP-XXX for the TO-247.

Just to make sure you're all on the same page.

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Old 11th November 2008, 11:25 PM   #554
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I think that is the page I am on. But to clarify, if I use the BrianGT board with one IRFP250 on each side (since the base BrianGT board holds is for a single set of TO-247's) instead of the two IRFP240's in the J schematic, I should be close.
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Old 11th November 2008, 11:33 PM   #555
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Quote:
Originally posted by Magura



......

Magura

just checking ......

your mail is working?
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Old 11th November 2008, 11:38 PM   #556
Magura is offline Magura  Denmark
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Quote:
Originally posted by Zen Mod



just checking ......

your mail is working?

something tells me it isn't

Could you go through my website?


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Old 11th November 2008, 11:45 PM   #557
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Quote:
Originally posted by Magura



something tells me it isn't

Could you go through my website?


Magura

I'll try in next few mins , to fwd last few sent ;
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Old 11th November 2008, 11:52 PM   #558
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Thanks Magura! . Mine are IRF250's after all as I checked, confirming your info - they are in TO-3 packages. I will share my stash with others here in the Bay Area. No more dust!
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Old 11th November 2008, 11:53 PM   #559
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Quote:
Originally posted by hayenc

I agree. The BrianGT boards look like they will work for this.

This solves the issue for creating an Aleph J. It seems the guys are creating a version of an Aleph JX with their old AX pcbs.


Fun stuff.
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Old 12th November 2008, 01:38 AM   #560
Variac is offline Variac  United States
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Maybe we should split off the Aleph XJ discussion?
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