Pass Aleph 2 with IRFP 140.

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Hi all.
I am fast approaching completion of my Aleph 2 amplifier, and would like comments regarding the usage of IRFP 140 devices.
I will be running about +40 to 45 vdc rail.

According to the data sheet, this should be OK.

My choice for this device is based on nothing more than having hundreds of these devices here ready to go. (Subject to matching).

Could someone please tell me if the usage of this device will be OK?

Kind regards.
George
 
Official Court Jester
Joined 2003
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two red dots

also - instead of 390R resistor , put 500R multiturn pot (preset to 390 or so ohms) , for fine output offset set
 

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just go for it

consider decreasing gate resistors to 150-180R

observe stability

don't skimp on 1nF anti-oscillation caps

to vivanco - 500mV across 1R source resistors

Hi Zen Mod.
Thanks for your advice.

The circuit that you requested is exactly as shown in post 7.

Also the 1nf caps that I am using are Roderstien metalized polypropylene.

The source resistors are currently 221 ohm, and there is no problem in reducing them to 150 to 180 ohm.

What advantages do you see in reducing the value of the source resistors?
Kind regards
George.

Ps: here are some pics of the boards.
 
Official Court Jester
Joined 2003
Paid Member
OK , pics still pending

140 is having slightly more capacitances than 240 , also greater xconductance , so Mueller effect resulting in harder (capacitive) load to preceding stage ...... means lesser/shorter bandwidth

to counteract that , decrease slightly gate resistors , observing stability

whatever , I think you're most probably good for.

........when you spend enough 140's in amp , rest you can send to OPLDF :clown:
 
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