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Old 28th September 2004, 03:21 AM   #41
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Any opinion for above?
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Old 28th September 2004, 05:15 AM   #42
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Hi,

Stop crying...Can't have that...

Quote:
And hey, is it true that putting a 100nF from each heater terminal to ground help to reduce RF noise?
YES.

Quote:
And do I really need to use wires of the gauge just enough to carry the required current for heater wire?
No more metal than strictly necessary.

Quote:
Of course, I'll use solid wires & twist'em tight for the rectifier HT with AC, but I'm planning to regulate the voltage for the 4 singnal tubes...
Still. It won't hurt. Keep heater harness away from the signal path too.

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Hopefully, it'll isolate some of the noise generated by the rectifier tubes...
What noise?

Cheers,
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Frank
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Old 19th November 2004, 06:28 PM   #43
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Yeah! exams are finished !!

It was holding me for almost 3-4 months !!

And I finally got ONE better potted transformer (Paeco by HP I guess) and is much more powerful with proper primary windings (115+115= 230V).

But ther's no powerful-enough center-tapped sec. winding, but two powerful single windings.

So could you guys help me to design a hybrid rectification for this transformer?

I basically got 2 secondary windings found to be useful:

One is rated for 302V @ 0.2A, but the voltage seems to be too high for hybrid rectification to be used to obtain approx. 250VDC..

The other one is rated for 205V @ 0.25A (with a tap rated for 167V, but that's not a CT... let's ignore the odd tap and use the 205V one...) I'll use the 0V and 205V taps to use the winding as a single winding.

----- 0V
l
l
l---- 167V
l
----- 205V @ 0.25A

Here are the things that I have, to be used for the PS:

*12pcs 100ohm 50W Aluminium Clad Dale resistors. I can connect many of these to increase the resistance.

*Many EZ80 rectifiers.

*A pair of MKP 60uF 370VAC motor-run caps.

I don't have any more space on my chassis to add another large component, like a choke or a cap....

Please remeber that this SINGLE transformer will supply BOTH channels. I'll build TWO PSU, ONE for EACH cahnnel.

I'm finding it very difficult to design one by myself, because the PSU designer program is not available for hybrid rectification, and both tube and SS diodes/rectifiers are used in this... (tube rect. has higher forward V drop than the SS diodes.... Then how do I combine the two to obtain the same, single voltage? ).

Please help, please, please please !!!
James
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Old 23rd November 2004, 04:02 AM   #44
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Need help!! ......
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