[Amps] Step Start circuit - needed or not?

[Vic K2VCO]

The SB-1000 does not require a step-start. The transformer is designed so that the 
secondaries have enough impedance to protect the diodes and tube filament at startup. It 
also has a relay to protect the switch (at least mine, which is a late model, does).

Having said all that, I added a step-start to mine to eliminate the thump that it 
sometimes emits on startup. But I think that's only an aesthetic thing.

On 2/23/2010 5:06 AM, Chuck Chandler wrote:
> I'm the new owner of a Heathkit SB-1000 amp, running it on 120 VAC.  It is replacing my
> AL-811.  When I bought the 811 I also bought an Ameritron Inrush Current Protector, and
> have always used it to turn the amp on and off.
>
> Now with the SB-1000 and reading recent posts on-line, I am wondering if I need the
> inrush current protector?  I am considering installing a step start circuit inside the
> SB-1000, which will do the same thing... but I am not sure it is necessary.
>
> I'm reading that the turn-on surge is only likely to really stress the power switch,
> and the SB-1000 switch is rated at like 18A, well over the normal current, but who
> knows how high it spikes when the caps are getting that first cycle?  And, of course,
> that's only for a very brief time.
>
> So, is a step-start of some type really needed?  If so, why don't more amps come with
> it?
>
>
> 73 de Chuck, WS1L

-- 
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/