[Amps] HV Diodes

Steven Katz stevek at jmr.com
Thu Oct 16 16:22:34 EDT 2014


The Alpha bridge modules discussed below are these: http://www.deantechnology.com/pdf/pdf24.pdf

It's P/N 2HVFWB5KB and uses glass passivated rectifier cells which are not 1N4007s, but ratings are similar.

Adding heat sinking and potting material around semiconductors doesn't change their surge rating in any way.  The surge rating is an instantaneous rating based on a 8.33 mS half sine wave and with or without any sort of heat sinking, this won't change.

-WB2WIK

-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of Manfred Mornhinweg
Sent: Thursday, October 16, 2014 12:48 PM
To: Amplifier Mailing List
Subject: Re: [Amps] HV Diodes

Carl,

 > Suffice it to say that the real world of tube type ham amps uses the 1N5408  > almost universally no matter what the configuration.

Do the Alpha 8410, 9500, 8406, and the 89 belong into the real world of tube type ham amps? I would say, they do. And they don't use the 1N5408 but instead use a potted bridge rectifier, rated at 5kV peak inverse voltage and 2A total 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 made from 1N5408 diodes would have a rating of 6A total.

This is it:

http://www.rfconcepts.com/REPLACEMENT-PARTS-LISTED-BY-ALPHA-PRODUCT/Blowers-and-Fans_2/HV-Bridge-Rectifier

Maybe it doesn't use the 1N4007, but then certainly it uses some other diode very similar to it, and not at all like the 1N5408.

They rate it for 50A surge of 8.3ms duration, which might mean the diodes inside are slightly beefier than the 1N4007, or maybe the difference is just due to to larger thermal mass thanks to the potting. If different, this could be 1N5622 diodes, which have that 50A surge rating. But that diode has a slightly higher voltage drop, which isn't consistent with the bridge's rating for voltage drop - while the 1N4007's is consistent with it!

I suspect this bridge is simply made from 1N4007 diodes, nicely potted, and sold for $150...

Take $2 worth of diodes, a little plastic case, 4 blade terminals, 20 drops of solder, and a few grams of a good epoxy potting resin, put it all together, and sell it for $150 to hams.  Hmm, I should get into that business! ;-)

On the other hand I do admit that several other amps I checked, indeed use bridges made from 1N5408 diodes. But the Alphas are too important an exception, to ignore them!

Manfred

========================
Visit my hobby homepage!
http://ludens.cl
========================
_______________________________________________
Amps mailing list
Amps at contesting.com
http://lists.contesting.com/mailman/listinfo/amps


More information about the Amps mailing list