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Fw: [Amps] Step Start on a 3KA Amp

PA3DUV
 

----- Original Message -----
From: "PA3DUV" <pa3duv@...>
To: "Ian White GM3SEK" <gm3sek@...>; <amps@...>
Sent: Wednesday, September 20, 2006 9:27 PM
Subject: Re: [Amps] Step Start on a 3KA Amp


Ian,

A picture of the Emtron switched mode softstarter + schematic diagram are available at:



I've heard that Emtron is selling their softstarter as a seperate item. This softstarter is a small switcher which chops the AC voltage, by doing so limiting the inrush current.

Cheers, Dick
PA3DUV


----- Original Message -----
From: "Ian White GM3SEK" <gm3sek@...>
To: <amps@...>
Cc: "Bob Maser" <bmaser@...>
Sent: Wednesday, September 20, 2006 11:33 AM
Subject: Re: [Amps] Step Start on a 3KA Amp


Bob Maser wrote:

Please remember that this thread started by me asking about a step
start in a 30+ year old amplifier from Henry, the 3KA. There are a lot
of things that could have been done differently in this amp but it is a
rock solid amp that will put out the legal limit and then some all day
long.
Could someone point us to a schematic, please? (BAMA doesn't have it.)


--
73 from Ian GM3SEK

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Amps@...
 

I've heard that Emtron is selling their softstarter as a seperate
item.
This softstarter is a small switcher which chops the AC voltage,
by doing
so limiting the inrush current.
Seems to me like the inrush shock to the PS lasts well more than
1/180th of a second (2 crossings every full 60 Hz cycle). If their
step-start uses SS zero-crossing devices, that means full current is
applied 90 degrees (+/- PF) after the moment the ON button is pressed.
That's an awfully large amount of current in a very short period of
time.

Unless there's some documented evidence that proves current is
reasonably limited with the use of these SS crossing devices, I think
I'll stick to relays and power resistors.

Paul, W9AC

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