Re: [Amps] HV Diodes

["Carl" <km1h@jeremy.qozzy.com>]

I wouldnt use smaller than a string of 1N5408's as they have a much higher 
surge current capability as the rather obsolete 1N4007 in the era of much 
higher filter cap C and dirty AC utility lines.
The diode leads are the heat sink and a minimum of 1/2" in free air is 
recommended by the manufacturers. Ive no idea how potting would modify that. 
My own method is to simply mount them on perf board when possible and thats 
easy in the Alpha 77DX in place of the "petrified blocks".
Carl
KM1H


----- Original Message ----- 
From: "KA4INM radio" <ka4inm@gmail.com>
To: "amps" <amps@contesting.com>
Sent: Wednesday, October 08, 2014 9:36 AM
Subject: Re: [Amps] HV Diodes


> On 10/08/14 06:35, Chris Wilson wrote:
>
>   When companies pot a string of 1N4007's (1 kV at 1 Amp) they rate the 
> string at .75 Amp.  The diodes, lacking the posts or copper foil to act as 
> heat sinks, run hotter when potted.  Short leads to the circuit board 
> copper conduct heat away from the silicon die better than long leads.
> > Hello Han,
> >
> > On Wednesday, October 8, 2014,  you wrote:
> >
> > > hi George-san and all
> > > I think HV6-1 is equivalent to GI HVPR10-MX12.
> > > I have measured forward voltages of these diode modules
> > > using a CVCC power supply with 100-mA current.
> > > Assuming each of the diode in a string exhibits 0.7 V forward
> > > voltage one can presume how many series diodes are in
> > > the module.
> > > GI HVPR10-MX12 6.36 V: 9 diodes
> > > EDHD 15k 10.67 V per a leg: 15 diodes x 2 (which I am using)
> > > SEMITECH KV-PAC SDHD-15k 12.97 V per a leg: 18 diodes x 2
> > > Toshiba S5166A (13 kV 500 mA) 14.0 V: 20 diodes
> > > I think 10 x 1kV 1A diodes in series is OK as an alternative.
> > > de Han JE1BMJ
> > Has  anyone  experimented  with  home "potting" diode strings to make
> > their  own  blocks?  I  am  curious  about diode lead length, physical
> > orientation, and potting compound used. thanks.
> --
>   Ron  KA4INM - Youvan's corollary:
>                 Every action results in unwanted side effects.
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