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Re: [N8VEM-S100:3947] Re: Power distribution across an S100 Board and voltage issues with TO-3 Regulators..

On Wednesday, June 4, 2014 6:52:50 AM UTC-5, Tom Lafleur wrote:
I've been using UTSource for over 4 years, many order for older parts, never had an issue.

I will agree that when I've been ripped off, it has NOT been by utsource.  Not yet.  And I have bought a variety of pure unobtanium from them as a last resort and its worked.  So far.
But no matter where you get parts, there is always a chance of bad parts. 

I've heard from several people and personally experienced the failure rate approaches 100% if you buy cheap generic 323K from that (other?) place in CA and its near 0% if you purchase the super expensive .mil and aerospace single sourced TI product that's a mere $40 a piece.

I should point out that the TO-220 package is historically accurate for the 70s/ 80s, I'm not wiring in surface mount d-paks or whatever.  "Something" on the regulator process line HAS changed in the last 30 years such that the thernal impedance has dropped from an unusable like 10 C/W in the 80s to 3 C/W now.  I'm puzzled how they pulled that off.  Maybe the dies are sliced thinner or they're doing something very strange with die attachment.  Probably a combination of multiple newer technologies.  I remember seeing junction-package thermal impedances in the (late) 70s datasheets for TO-3 transistors that were higher than modern TO-220 specs, which seems crazy but true.