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alexg 9th April 2008 02:51 PM

Hybrid Graetz Bridge
 
I built a PP KT88 with SS rectification and there is a huge turn on thump.

I tried ICLs, reducing PSU capacitance, caps across the switch and other ways to remove the thump and I am very unsuccessful. I don't want to build a mute circuit.

I have a 5ar4 rectifier which is rated at maximum of 250ma at 375VAC input. (I only have space for one rectifier tube on my chassis).

I need more than 250ma, would using a hybrid Graetz bridge increase the current capability of the 5AR4?

Thanks.

Sheldon 9th April 2008 03:25 PM

Re: Hybrid Graetz Bridge
 
Quote:

Originally posted by alexg

I need more than 250ma, would using a hybrid Graetz bridge increase the current capability of the 5AR4?

No, but you could put a single 6cg3 damper diode after the bridge for a slow turn on. I think they are rated for about 350mA DC, and would drop about 20V. There may be others too.

Sheldon

alexg 9th April 2008 03:28 PM

Re: Re: Hybrid Graetz Bridge
 
Quote:

Originally posted by Sheldon


No, but you could put a single 6cg3 damper diode after the bridge for a slow turn on. I think they are rated for about 350mA DC, and would drop about 20V. There may be others too.

Sheldon

Thanks Sheldon.

Can I parallel two 5ar4 to get more than 250ma?

Sheldon 9th April 2008 03:45 PM

Well, I've seen the plates paralleled, so by extension it should be fine to parallel two tubes (4 plates). But if you are going to do that, just parallel the plates in each tube and go back to the the hybrid bridge with two tubes. And if you are going to do that, just use two damper diodes like a 6AU4.

Sheldon


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