Wierd Voltage reading with EH toroidal transformer? Someone double check me?

[william]

I recently put together my project I've been wanting to build for awhile now.  It uses a EH toroidal two provide power to two tubes.  I got everything assembled and made voltage measurements along the way.  The schematic looks like this,


When I measured the voltage immediately after the rectifier bridge minus any other parts I got appx 250VDC.  After putting C21, R21, and C18 in I measured again and got appx 300VDC.  Now with all the parts in place minus the tubes I am measuring appx 450VDC at the first node.  Is this even possible.  I didn't leave it plugged in very long because the capacitors I used are only rated for 450V.  I didn't plan on the voltage being that high.

Also I'm planning to put a resistor across C21 to help bleed the voltage when it's turned off.  I had to use my multimeter to reduce the voltage from 400 to .45vdc and it took about 20 minutes.  Whats a good value to use for something like that?

[A.S.P.]

put in the tubes, and measure again...

[william]

Right, I understand that the tubes will change the readings but my understanding is that it shouldn't alter them that much.  Also I don't believe the EH toroidal transformer is capable of generating that much voltage.

[A.S.P.]

putting in the tubes, will also load down the wallwart to its nominal voltage.
(especially if you heat the tubes from that ww.)
Unloaded, it might well be over 15V to 17V~, and hence this will be transformed up skyhigh...

never take an AC power-supply/wallwart nominal voltage for granted...
it`ll vary under load/noload conditions;
measure the input- and the output-voltage of the toroid simultaneously,
or at least under identical circumstances.