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Re: [Amps] HV Diodes

To: Amplifier Mailing List <>
Subject: Re: [Amps] HV Diodes
From: Paul Christensen <>
Date: Thu, 16 Oct 2014 16:14:35 -0400
List-post: <">>

Regarding Alpha, the 77Sx (dual 8877) uses a quad set of Semtech SCH5000
modules rated at only 5KV/0.5A.  The current rating is increased to 1A
with forced-air cooling.  I¹m sure these have failed owners at one time or
another but they seem to have held up well for most 77/70 amp owners.  If
mine ever blow, they¹ll get upgraded to slightly better specs at that time
but nothing greater than the equivalent of six 1N5408 types per leg.

I¹m all for ³super-sizing² components, but not until a circuit¹s minimum
safe limits are calculated.    Over-sizing for the sake of over-sizing
seems like a lazy way to impress friends!

Paul, W9AC

-----Original Message-----
From: Manfred Mornhinweg <>
Date: Thursday, October 16, 2014 at 3:47 PM
To: Amplifier Mailing List <>
Subject: Re: [Amps] HV Diodes


 > Suffice it to say that the real world of tube type ham amps uses the
 > almost universally no matter what the configuration.

Do the Alpha 8410, 9500, 8406, and the 89 belong into the real world of
type ham amps? I would say, they do. And they don't use the 1N5408 but
use a potted bridge rectifier, rated at 5kV peak inverse voltage and 2A
forward current. I don't know with certainty what's inside it, but 4
strings of 
5 each 1N4007 diodes would have exactly those ratings. Instead a bridge
from 1N5408 diodes would have a rating of 6A total.

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