Peter Chadwick wrote:
>One problem that can arise is if the psu doesn't like providing the
>excess amps when you first switch because the filament is cold. I got a
>5v 15A one for my 4CX1000 (yet to be built) amp: it won't start with a
>cold filament. It's possible some constructive step start or voltage
>ramping is needed.
Voltage ramping can sometimes be as simple as "slugging" one side of the
master potential divider with a large electrolytic, but it still doesn't
guarantee that the switcher will allow itself to start at near-zero
voltage output. Some will, some won't.
The add-on circuit posted by WC6W yesterday looks like a good solution,
because it allows the switcher to start up as normal, and then gives a
gentle ramp of current into the tube.
Nice one, Marv:
http://wc6w.50webs.com/wc6wamps/index.html?fr64.html
--
73 from Ian GM3SEK
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