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Help for 211 HV PSU with damper diodes

crazyfrog

Member
2009-05-31 2:35 am
Being inspired by Thomas (vinylsavor) damper diodes PSUs, I decided to build a new supply for my 211 amp with two 6DW4s and no electrolitics. I have already a Hammond 724 (750-0-750) and two 12 Hy/100 mA chokes. Each one was going to each triode until now and the 211s are DC heated by an individual transformer. The diagram is similar to Thomas' Single Ended Amplifier Concept. I'd like to use just two damper diodes.
Thanks
Pierre
 

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Rundmaus

Member
2005-08-21 10:46 pm
Hey there,

with a choke-input supply, you'll get a DC output voltage of approx. 0.9*U_AC, so this will be roughly 680V minus the forward voltage drop of the damper diodes.

You will not get the 900V mentioned in your schematics - maybe try and play around with PSUD II software...

Greetings,
Andreas
 
Hi Pierre,

as mentioned by Andreas, you will not get the 900VDC with choke input.

With such high voltages, power transformer and first choke will tend to mechanically buzz a lot. Cap input will reduce that dramatically. That is the reson why I use cap input (with small input cap) with my 211 amps

I would use a cap rated for 2kV as the first cap.

Best regards

Thomas
 

crazyfrog

Member
2009-05-31 2:35 am
Hi,

using silicon diodes will not change anything with regard to the remarks above. They only have a little less voltage drop, but the TV dampers have very low voltage drop anyways.
The 6DW4 cannot really be used for smoothing. Or do you mean slow ramp up of the B+

Thomas

I can use a bigger cap before the choke after silicone diodes compared to a tube rectifier(even if there is a limit to raise the voltage using this method).

I called "smooth" the 6DW4 meaning it rises the voltage smoothly :D .

There is something else I didn't think to say. The Hammond 724 is rated 115/1500 but I have 120V at home (and usually you can expect higher rating with Hammond). Don't remember what is the exact voltage but it's pretty high (Not at home for the moment but I'll check).

Thanks
 

crazyfrog

Member
2009-05-31 2:35 am
Hey there,

with a choke-input supply, you'll get a DC output voltage of approx. 0.9*U_AC, so this will be roughly 680V minus the forward voltage drop of the damper diodes.

You will not get the 900V mentioned in your schematics - maybe try and play around with PSUD II software...

Greetings,
Andreas

I did simulations with PSU II. Voltage is more like 800V-0-800V with 117V at primary (-10°C here, lower mains voltage). Used 6CJ3s (6DW4 not available) and RL=5,6k. Started with a small 10µF cap after diodes to avoid "buzzing" followed by my two 12Hy in parallel to make it simple. Put 50 µF 1250V Solen caps (two 100 µF, 630V in series) and another 6Hy, etc...No problem with voltage amplitude. Will even have to play with power resistors.
Thanks.