It appears as though no one answered you, at least not on the reflector.
I'd question the sanity of homebrewing rectifier boards when K2AW's modules
are so cheap, are well insulated, and work great. I use them all the time,
in many amps.
But if you insist, the industry rule of thumb for FR4 and air isn't much
different, at 10,000V per inch, or 1kV/.100" for creepage.
WB2WIK/6
"Each success only buys an admission ticket to a more difficult problem." --
Henry Kissinger
> -----Original Message-----
> From: Jim Barber [SMTP:N7CXI@SiliconPixels.com]
> Sent: Saturday, November 17, 2001 9:25 AM
> To: amps@contesting.com
> Subject: [AMPS] 8877 rectifier board considerations
>
>
> Hi folks,
>
> I'm at the point where I'm laying out the B+ rectifier
> board for my 8877 project, and it occurs to me I don't
> know much about component spacing for high-voltage (2800
> VRMS, 3900VDC typical) applications.
>
> Considering a .062" (~ 1.6mm) FR-4 epoxy PCB and typical
> environmental conditions, (dust, humidity, altitude, etc) I'm
> wondering what a good rule of thumb would be for minimum spacing
> between the diode strings? For space and PCB cost considerations,
> I'd like to lay the strings out more-or-less parallel to each other.
> There's six 1N5408 diodes in each string, (FW bridge) with no
> equalizing components.
>
> I realize the potential differs between points, but if
> I wanted to assume that the peak voltage existed between every
> point on the board, what would be a conservative spacing? The
> dialectric constant of the FR-4 material runs between 4.2 and 5.0,
> and there's the air-gap to consider as well.
>
> Thanks,
> Jim, N7CXI
>
>
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