In Reply to: Re: Thank you! RH Designs SEP EL84 build is done posted by mwiebe on March 27, 2007 at 19:16:46:
Thanks for the feedback. Everything was simulated in PSUD2 before construction. The simulations ran fine with no errors, although I will admit that the surge current is quite high (well within the specs of the UF4007 diodes but certainly difficult on the transformer). The CL90 should be limiting the surge current somewhat. Had I stuck with the tube rectifier, I would have been limited t0 <50uF in the first stage.Anyhoo, I'm new to pentodes - I think the reason I was seeing 120Hz on the output was due to the suboptimal power supply and unregulated screen supply (a few here pointed out this possible problem). The quick fix was to really stiffen up the B+ supply by adding more capacitance. The better way (I admit) is to use the recommended CLC filter and possibly regulate the screen supply using one of the methods mentioned in the earlier post.
I know it's a little extreme to use 430uF in the first stage. Maybe I'll fiddle around with it more and try to shoehorn the choke in and pop out the extra 390uF cap that I added to the first stage.
Again, thanks for the feedback.
-Matt
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Follow Ups
- Re: Thank you! RH Designs SEP EL84 build is done - eedork 19:37:03 03/27/07 (3)
- Re: Thank you! RH Designs SEP EL84 build is done - mwiebe 20:00:40 03/27/07 (2)
- 120 Hz hum - eedork 05:37:57 03/28/07 (1)
- Re: 120 Hz hum - mwiebe 18:00:50 03/28/07 (0)