Pi Filter Behavior in a Unregulated Power Supply (u47)

[StormsofVogue]

Hello. I'm trying to understand a behavior with a power supply I'm working on. With the C1 capacitor connected (highlighted in red), I get a voltage increase across the whole circuit. It jumps from 105v to 140v under load measuring at the output. R1 is a choke (not resistor). My understanding is that C1/Choke/C2 form a Pi filter. Is it normal to expect a voltage increase with C1 connected in this circuit? I'm not really sure what's happening.

Details and context here.

 

[Lampie519]

This is a normal behavior as without the capacitor the voltage is not yet smoothed out DC but actual a kind if AC still.

 

[StormsofVogue]

This is a normal behavior as without the capacitor the voltage is not yet smoothed out DC but actual a kind if AC still.

Thank you so much!

 

[Tubetec]

A larger first filter cap leads to better smoothing of the waveform and so a higher DC voltage output .
Adjusting the cap value is a handy way to trim your HT voltage without the need to juggle the series resistances , of course tube rectification will have a maximum value of first filter cap and its never a good idea to exceed that reccomendation as it can reduce the lifespan of the tube or even cause catastrophic failure .