Stealth vs. Hexfred Diodes

[xoaphexox]

When performing upgrades of power supplies in devices like tuners and amplifiers I have seen people use fast diodes - there are two types in particular which I didn't realize until today were actually two separate lines. I had heard the term 'stealth hexfred' diodes - apparently they are actually two separate lines.

I use them in a KT-8300 and PunkerX used some in my TU-919 and I have had no problems with them...

I am curious what the difference would be in practice in the context of upgrading a power supply in, say, a Pioneer SA-9100.

Thanks.

Stealth Datasheet:
http://www.fairchildsemi.com/ds/IS/ISL9R860P2.pdf

Hexfred Datasheet:
http://www.vishay.com/docs/94047/hfa08tb6.pdf

 

[Tom Bavis]

Based on the data sheets, I'd pick the Fairchild because it is specified for avalanche energy - it should withstand overvoltage spikes better than most. That's a specification I always look for. Both of these will have minimal switching noise in a 60 hz application.

 

[xoaphexox]

Thanks for your input, Tom

 

[33&athird]

Based on the data sheets, I'd pick the Fairchild because it is specified for avalanche energy - it should withstand overvoltage spikes better than most. That's a specification I always look for. Both of these will have minimal switching noise in a 60 hz application.

Interesting, I always kind of assumed a diode was a diode...I'll have to look into this, I haven't heard of uF diodes, all i've heard of is schmitt trigger circuits. Learn something new everyday, so thanks for bringing it up:yes:

Out of curiousity, on some amps, wouldn't that 60hz switching noise be even more minimized by an inclusion of a 10nF or so filter cap in parallel to the diode? I have been doing that in my power supply designs after picking it up in a pioneer manual.:scratch2:

 

[xoaphexox]

In the SA-9100 in question the rectifying diodes are bypassed by .01uF ceramic caps which I have seen bypassed by poly caps instead (as an 'upgrade') but never tried that myself. I have an SA-9100 torn down on the bench right now that I may just try it out on...

 

[33&athird]

In the SA-9100 in question the rectifying diodes are bypassed by .01uF ceramic caps which I have seen bypassed by poly caps instead (as an 'upgrade') but never tried that myself. I have an SA-9100 torn down on the bench right now that I may just try it out on...

Sounds about right. the .01uF translates to 10nF, which seems to be the pioneer standard value for diode noise suppresion. Ceramic caps I would think are okay for this application, as they only act as couplers...and are in the power supply. Of course, poly caps are better quality, but I can't imagine any better effect. Maybe the ceramics have a little extra noise, but I doubt there is a difference.:scratch2: If anything, would think film caps would be better, but I haven't looked into noise and other ratings.

These uF diodes are very neat...i've been looking them up. Next project is getting the uF diode treatment. I love trying new things and building power supplies, so this is great:yes: