----- Original Message -----
From: "John Rabson" <[email protected]>
To: <[email protected]>
Sent: Thursday, January 22, 2004 4:11 PM
Subject: LF: Re: SOFT START
It's when a bank of capacitors totalling a quarter of a Farad at 24 volts
is
connected with wrong polarity that things start to get spectacular.
How could that happen, impossible except the constructor had too much
GLENGARRAGCT Mc NAHT
73
John G3PAI
----- Original Message -----
From: "hamilton mal" <[email protected]>
To: <[email protected]>
Sent: Wednesday, January 21, 2004 2:53 PM
Subject: LF: SOFT START
Hi All
Surprisingly, most high power amps do not have a SOFT START, and judging
by
the thump at times on switch on, it is even more surprising that the power
supply does not explode. In recent times I use a variac and gradually
adjust
it to full voltages.
This is overkill and a more simple cct would suffice. I lost one mains
transformer a few years ago and the replacement cost more than the amp was
worth. Some of the PSU'S for low voltage high current FET AMPS used in LF
applications are even more vunerable ie 12 - 24 V at 20 - 100 A. Most
Amateurs that I have spoken to do not realize the danger involved. One of
the bean can size electrolytics 200 mfd capacity exploding would be like
firing a mortar, probably demolish the house in some cases. The stone
built
country house would probably survive.If you are dabbling with QRP there is
no need to worry.
73 de Mal/G3KEV
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