Freds Power Supply for Aleph

[louischia]

Good day everyone!
I'm in the process of finalizing my Aleph 2 PCB design and partlists. I do found quite a number of discussions about using freds for PS in the forum. Sorry for my ignorance... do i use these freds just like any other rectifiers? I know that freds are better in terms of component audible noise. Can I just replace the rectifier diodes in my PS with them? Does any nice souls out there with a nice schematic or PCB layout with partlists using freds to share? I'll be using a 2x37v 1kva toroid per mono. Which model of freds should I use?

[massimo]

Originally posted by louischia
do i use these freds just like any other rectifiers?

YES, as any other TO220 diode

Which model of freds should I use? [/QUOTE]

Depends on the maximun current you draw from P.S.
According to your Xfrm, you can draw up to 13 A per rail.
A safe value could be 13 x 3 = 39 A diode.
Not considering that if you use a lot of caps, the surge current can be huge when you power up the amplifier.

The biggest Hexfred from I.R., as far as I know, is the HFA25TB60, a 600 V / 25 A device.
A bit too small even if you plan to use 2 different bridges, one per rail.

[louischia]

so wat should i use?
any recomends frm the forum?
wat r others using den?

[louischia]

looks like lots of viewers but no replies...
where r all those ppl tat built the Alephs? U guys don't use freds for PS? Wat about other state-of-art amp builders?

[UrSv]

Depends on the maximun current you draw from P.S.
According to your Xfrm, you can draw up to 13 A per rail.
A safe value could be 13 x 3 = 39 A diode.
Not considering that if you use a lot of caps, the surge current can be huge when you power up the amplifier.

The biggest Hexfred from I.R., as far as I know, is the HFA25TB60, a 600 V / 25 A device.
A bit too small even if you plan to use 2 different bridges, one per rail.

Actually I think the 25 A are continuous and the Ifrm is something like 100 A and peak is 250 A. That diode would be just fine as would many others.

[Peter Daniel]

With a proper inrush supression circuit, 25A diode should be fine. You might use separate bridge per rail.

[Boxbldr681]

I run a Tube R.F amp that runs 2 - 4CX1500A7 ceramic tubes at 4,200 volts DC at about 1.5 amps with a homebrew square wave rectifier board with 12 1N4007's per leg with no problem at all. Do note the inrush protection circuit and 470K 1wt resistors with .005 5KV ceramic caps per diode. I use this old rig to pump out 2,700 watts of *** kicking 27 MHz A.M. broadcast here in Vegas when ever the need is there. Poor skip land. I do use your basic diodes for high voltage mostly, not much need for big amps in R.F. work.