[Amps] Rectifier equilization?

[Carl]

I havent bothered with resistors on a 1N5408 in over 25 years. A cap across 
a single diode or bridge block can eliminate switching noise but it doesnt 
do much in a long string.
Instead use a .0047/.005 across the full string and another to ground at the 
output.
This also bypasses line spikes around the diodes and to ground. Be sure to 
use quality caps, not some blue Chinese crap from Fleabay and hamfests.

Carl
KM1H



----- Original Message ----- 
From: "peter chadwick" <g8on at fsmail.net>
To: "Hardy Landskov" <n7rt at cox.net>; <amps at contesting.com>
Sent: Friday, September 13, 2013 1:48 PM
Subject: Re: [Amps] Rectifier equilization?


> If they are off the same reel, you should be OK without resistors. 1N5408s 
> are pretty slow, so I don't think you need capacitors, either. But an MOV 
> on the transformer primary and step start are good for minimising  stress 
> on everything.
>
> I did work at a semiconductor company where they made diodes - nothing as 
> small as a 1N5408 though, but diodes rated at 2000 amps and 1500 volts 
> PIV. The guys there told me that devices from the same batch shouldn't 
> need equalising resistors
>
> 73
>
> Peter G3RZP
>
>
> ========================================
> Message Received: Sep 13 2013, 05:28 PM
> From: "Hardy Landskov" <n7rt at cox.net>
> To: amps at contesting.com
> Cc:
> Subject: [Amps] Rectifier equilization?
>
> I have just rejoined the amp list after a few years and am wondering if 
> the diode equalization question was ever resolved.
> I am building a new bridge HV PS and it uses 12 diodes per leg. Rich 
> Measures says using a .01 & 470K across each diode is no longer needed due 
> to improvements in semiconductor manf. processes.
> I have 100 1N5408's that came off the same reel so I feel they should be 
> matched fairly close.
> I would like to hear a few opinions.
> Thanks
> 73 Hardy N7RT
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