Guys:
Let's make one thing clear: in our present culture, when suing is so
prevalent, you're in danger whenever you leave the house. it's definitely
possible to use a separation transformer during the initial commissioning,
but the point is to make a smaller and lighter amplifier.
If you look at your washing machine for example, you'll find a
control board for the motors and the water admission system working of line
because of the relatively high power involved. And that is a commercial
piece of equipment! I think that our conditioning is acting here more than
anything else: it's a carryover from the high voltage supply era.
Like I said in one of my previous letters: any switching power
supply you pick up is working just like that: active power electronics fed
directly off line and a transformer isolated output. What's different in a
SSPA? A transformer isolated input?
AND PLEASE, GUYS: don't involve kV power supplies in this! The
problems encountered there are totally different: corona, high electric
fields- and I mean high- isolation withstand, creepage..... these are not
issues at 300-400 volts. Protection circuits too, they are a special breed
of circuit, full of transients due to their quick disconnect features.
Alex 4Z5KS
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of peter chadwick
Sent: Saturday, October 05, 2013 7:00 PM
To: Manfred Mornhinweg; amps@contesting.com
Subject: Re: [Amps] Direct rectification of AC mains to drive the amp,
Manfred,
Over here, unhooking the scope ground lead would, in an industrial
situation, let all hell loose with Health and Safety! It would lead probably
to suspension before dismissal, and could conceivably even lead to criminal
prosecution....especially if anyone got a shock.
Of course, as a temporary measure, one could drive the amplifier from an
isolating transformer while measurements are made......then you could have a
grounded 'scope and ground one of the amplifier supply lines. All much less
likely to give problems.
73
Peter G3RZP
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