2stageEF high performance class AB power amp / 200W8R / 400W4R

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Dear Arul,

nice to see a single sided pcb variant of the initial input stage of the SA2014 release (old name was SA2013). A better, safer and extremely stable version can be found reading the index (first post) and use the schematics from the links provided in step
A) SA2014 (200W@8R, 400W@4R)

BR, Toni
 
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case preparation - tools

... after several years of searching I found a simple hand tapping machine which saves me a lot of time (19 kg; up to 190mm wide so I can prepare metal plates which are up to 380mm wide).

BR, Toni
 

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I've tried just about every tapping machine available over the years and still prefer a good quality cordless drill....

The small part I showed above is stainless steel 3mm thick. I have done a few with my li-on power drill but never got it exactly 90 degree...
Using a cordless drill oder li-on power drill for M3 is a nightmare because you can easy destroy your M3 tapping drill and therefore convert your expensive heatsink to cheap metal waste.
 
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... after several years of searching I found a simple hand tapping machine which saves me a lot of time (19 kg; up to 190mm wide so I can prepare metal plates which are up to 380mm wide).

BR, Toni

How well does that work with small threads, such as M3?
I currently use a T bar tapper as shown in the attached picture. That works fine although you need to be careful to tap straight into the hole.
 

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SA2015 4 channel VMOS - case layout

... frontpanel is inserted ... easy removeable ... all parts fit so far ... puuuh :)
 

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The small part I showed above is stainless steel 3mm thick. I have done a few with my li-on power drill but never got it exactly 90 degree...
Using a cordless drill oder li-on power drill for M3 is a nightmare because you can easy destroy your M3 tapping drill and therefore convert your expensive heatsink to cheap metal waste.

I do M3 in heatsinks all the time with no issues. There are a couple key things needed to be successful though. The heatsink needs to be real aluminum (T6063-t6) not the Ebay crap with all the garbage in it and it needs to be drilled with a sharp drill bit with coolant so the aluminum doesn't get hot and anneal.
 
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The problem is not the heat. I too use a special drill lubricant.
The problem is the exact 90 degree angle and trembling fingers of an "old" man ... crack ... drill bit is gone ... heatsink too... :eek:
BTW: I do not use cheap heatsinks. They are made by cooltec and length cutted by them exactly for my needs! Best you can get!
 
The problem is not the heat. I too use a special drill lubricant.
The problem is the exact 90 degree angle and trembling fingers of an "old" man ... crack ... drill bit is gone ... heatsink too... :eek:
BTW: I do not use cheap heatsinks. They are made by cooltec and length cutted by them exactly for my needs! Best you can get!
I use a base drill and then,after drilling,a hand tool for tapping.
Yes isn't an easy way for 90 degree angle perfect tapping.
 
I guess this depends on how often you tap holes. This is a daily thing for me for 25+ years. I can tap perfectly straight (or straighter than the threads on the fastener) with a Milwaukee cordless drill. It I try to use one of those crappy T-handle tap wrenches I get it crooked just about every time. The extra length of the drill allows me to judge the angle a lot easier.
 
I guess this depends on how often you tap holes. This is a daily thing for me for 25+ years. I can tap perfectly straight (or straighter than the threads on the fastener) with a Milwaukee cordless drill. It I try to use one of those crappy T-handle tap wrenches I get it crooked just about every time. The extra length of the drill allows me to judge the angle a lot easier.
Yes Jeff, your guess is right!
My first attempt for tapping was some years ago.