• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Switch contacts for HV supply

So I'm upgrading my HV supply on my bench with this


I have a few wiring schemes figured out to get the following voltages after rectification: 250v, 280v,350v,390v,425v,450v.
I want to use a 6 position 2 pole rotary switch ( from radio shack) to give me the AC combinations I need before rectification, but am unsure if it is safe or not. The switch is rated at 125v 300ma. I think the most I would be pulling through it at 450v would be 150ma, and I wouln't operate the switch while on- only as a preset before the power is applied. Does anyone think I will have any problems with the high AC voltages jumping terminals or the high DC currents melting the contacts ( provided I am not operating the switch while the PSU is on?)
I would stay away from R-S switches for your purpose. They're nothing but cheap imported garbage. If you can't find a good ceramic rotary switch at a local surplus dealer or a hamfest fleamarket, then search eBay for "rotary switch" and you'll find some nice ones. Some are even available with buy-it-now. Try to get a non-shorting (break-before-make) style and you can switch with power on.

I can see if Fryes has one, their about 17 miles from me. I don't like to use radio shack stuff, but never had a failure with any of their parts since their relativley decent.

I am going to be building a completly tweak-able preamp with rotary switches for capacitors, I am going to get cheap 12 position single pole ones from AES because they are only $1.50 each... and cheap is important since they dont have to handle much voltage and I need uhh... 12 of them.

For diodes, since I need a FWB, won't 1n4007's work? With a 47uf input cap, will there be much hash? If so can I use a low value film cap to suppress this, or should I bypass each diode with a cap?