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  #1  
Old 26th February 2017, 06:49 PM
bikerhifinut bikerhifinut is offline
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Default What Silicon rectifiers for HT?

I'm going to rectify 330VAC off a toroid rated at 1A continuous (yes its a biggun!) but I'll only be pulling around 350mA for now although the design needs to be able to supply double at some point in the future.
I did think to use the good old UF5408 assuming I can find someone who will sell them in quantities less than 50! rated at 3A it should be fine as each diode in the bridge should only be passing 500mA if I remember my theory right.
Are there any other good quality not too expensive silicon diodes that could be recommended.
Also I will be sourcing some big 5 amp voltage regulators ( or use 2 x 3 amp and make individual regs for each output valve heater currently 1.5A EL34 but I want the option to redesign for KT88/100/120/150 if i get the urge and rich enough to afford some!
Cheers

Andy.
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  #2  
Old 26th February 2017, 08:34 PM
Richard Richard is offline
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Default Re: What Silicon rectifiers for HT?

Got a load of UF4007 here Andy if you want a dozen gratis, drop me a pm
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  #3  
Old 26th February 2017, 10:21 PM
bikerhifinut bikerhifinut is offline
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Default Re: What Silicon rectifiers for HT?

whats their rating Richard? Voltage current and recovery time.

I can look em up so no worries

A.
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Old 27th February 2017, 10:35 AM
Richard Richard is offline
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Default Re: What Silicon rectifiers for HT?

http://www.vishay.com/doc?88755

1000V 1A 75nS we used them for Kit88 tweaking but I don't know what you have in mind
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  #5  
Old 27th February 2017, 05:53 PM
bikerhifinut bikerhifinut is offline
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Default Re: What Silicon rectifiers for HT?

Thanks Richard.
I need something a bit beefier as there is potential for a big inrush current as the PSU Caps charge up. They will be quite big ones. And the Toroid is very over specified and capable of delivering a large load current.
So it's UF5408 as a bare minimum but I have a feeling from the advice given by the chap who wound the toroid that I need 6A minimum and that starts to be a big ask as the number of 1kV high current devices on the market is a lot less.
Plenty of time yet to get stuff together. I need a suitable chassis/case for this PSU and thats probably going to be the trickiest job. I can see me persuading one of my wood worker mates to make a nice framework to bolt a couple of substantial steel or ally plates top and bottom to support the heavy transformer.

A.
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  #6  
Old 27th February 2017, 06:25 PM
colin.hepburn colin.hepburn is offline
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Default Re: What Silicon rectifiers for HT?

Hi Andy
Have a look at the MUR range like the MUR880E 8A 800V Ultra-Fast Recovery Diode

http://www.futurlec.com/DiodesPower.shtml
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  #7  
Old 27th February 2017, 06:47 PM
bikerhifinut bikerhifinut is offline
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Default Re: What Silicon rectifiers for HT?

Colin: thanks
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  #8  
Old 27th February 2017, 07:01 PM
bikerhifinut bikerhifinut is offline
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Default Re: What Silicon rectifiers for HT?

Available for less from RSonline Colin. and free postage if you don't want em yesterday.

A.
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  #9  
Old 27th February 2017, 08:44 PM
bob orbell bob orbell is offline
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Default Re: What Silicon rectifiers for HT?

Quote:
Originally Posted by bikerhifinut View Post
Thanks Richard.
I need something a bit beefier as there is potential for a big inrush current as the PSU Caps charge up. They will be quite big ones. And the Toroid is very over specified and capable of delivering a large load current.
So it's UF5408 as a bare minimum but I have a feeling from the advice given by the chap who wound the toroid that I need 6A minimum and that starts to be a big ask as the number of 1kV high current devices on the market is a lot less.
Plenty of time yet to get stuff together. I need a suitable chassis/case for this PSU and thats probably going to be the trickiest job. I can see me persuading one of my wood worker mates to make a nice framework to bolt a couple of substantial steel or ally plates top and bottom to support the heavy transformer.

A.
How many are you wanting Andy, I have 4 Vishay UF 5408. 1000v 3a 75uS .BOB

Last edited by bob orbell; 27th February 2017 at 09:09 PM.
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  #10  
Old 27th February 2017, 09:35 PM
Richard Richard is offline
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Default Re: What Silicon rectifiers for HT?

No problem Andy, it's often difficult deciding how to rate a component but as a bench mark those little 1A diodes were fine with the toroid main TX on Kit88 filling series 470uF caps (=235uF) feeding 4 KT88s.

There are a few ideas in the FAQ
http://www.world-designs.co.uk/forum...read.php?t=210
but I see that was 11 years ago and some are no longer available.

The 1200V 5A schottkies back then were 80 set of 4 but you can get similar a lot cheaper now from RS if you fancy them
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