[Amps] Direct rectification of AC mains to derive the amp VDD, supply

[Alex Eban]

One thing to be stressed is:
	RFI/EMC issues have NOTHING to do with the existence of the input
transformer.
	All equipment is required to have RF bypassing at the mains input.
That's been true since before I was born, and that quite a time by now.
	Schaffner and a lot of others have grown rich by selling RFI filters
to all and sundry
If you stick to accepted rules we've been using for years, at least you
won't do any worse that before. You can always improve on that, but beware:
it's like the EL lamps story: more efficient, less noisy more compact but
nobody told you cheaper to make and more expensive to buy. Who exactly
profits? All this trend to throw the manufacturers' mishaps on the buyer
have to have an end .....
	The safety issue is settled at the transformers: even the most
stringent VDE standards call for about 2500 v withstand voltage, easily
achieved with Formvar wire, Teflon insulated wire or reasonable quality
coax. 
All you have to do is use your head when you poke inside the enclosure. Like
Heinlein said:" you learn and live. Or you don't".
Alex	4Z5KS


-----Original Message-----
From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of
donroden at hiwaay.net
Sent: Wednesday, September 18, 2013 2:11 AM
To: amps at contesting.com
Subject: Re: [Amps] Direct rectification of AC mains to derive the amp VDD,
supply

Quoting Jim Brown <jim at audiosystemsgroup.com>:
> These  fundamental requirements combine to make direct rectification 
> of the mains more than a bit impractical if you care about safety and 
> freedom from EMC issues.
> 73, Jim K9YC

Properly implemented, ( green to chassis ) ( neutral to neutrals), safety
and direct rectification don't have to be mutually exclusive.

Don W4DNR

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