>
>A few questions about voltage doublers. I'm building a single tube 4CX250R
>for 70cm using a voltage doubler
>supply. This is my first attempt at FWD supplies.
>
>I have a transformer with about 750vac secondary, 12ohms dc resistance.
>I'm planning on using IN5408 diodes and
>a string of electro's.
>
>(1) I can either use 5 x 190 uf 400vdc caps in each side of the stack,
>second hand, or 5 x 1500 uf 250vdc caps
>which are new but will give a much greater overall capacity. Is there such
>a thing as too much capacity in the stack,
>and will this make the supply too "stiff" if things go bang
>
? Perhaps. Mo' C is not always mo' betta.
>(2) Is modern practice to still put C and R across each individual diode
>in the rectifier stack.
>
? No. The new ARRL Handbook says 'equalizers' can lead to diode failure.
>(3) Is it good practice to place a diode across each cap in the stack,
>cathode towards the + side, for reverse current
>protection.
>
? Yes
cheers, Glenn
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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