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Joseph Meditz
 
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Hi John,

For a full wave CT rectifier one of the transformer HT leads usually has
more resistance than the other. So a line frequency component (60 HZ in NA)
arrives at the filter. The filter is less able to attenuate the 60 HZ than
the 120 HZ in the ripple, so could arrive at your filter output fairly
large. Have a look at the HT at the filter output. One easy fix if that is
the case would be to add a small resistance in the HT lead having the least
resistance so that the rectifier will see equal sources.


As I recall it, the ripple on the B+ looked fairly uniform. I don't
recall every other bump a different size. But I'll keep this in mind
the next time I do some measurements. Also, the AC voltage on both
sides of the center tap were equal on the DMM.

However, the 120 Hz ripple is a bit higher than the simulation results,
0.2 Vp-p vs. .12 Vp-p.


If you are using the chassis for the heater returns as some do you should
change the heater leads to twisted pair.


I would never use the chassis to carry as a current carrying return. I
do have twisted the heater wires and have positioned them close to the
chassis. Btw, on my next project just for fun I'm going to feed the
heaters with shielded wire.

The common of the amp & it's PS
should be connected to the chassis only at the signal input connector.


That's the way I have it.

Be
careful with the CT lead from the HT winding to the first cap. A serious
ground loop could develop altho in that case the interference would be at
120 HZ. Cheers, JLS


Thanks for your thoughts on this John.

Joe



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