[Amps] Step Start

[R.Measures]

On Aug 12, 2005, at 5:13 PM, gdaught6 at stanford.edu wrote:

> OK, the consensus response to my question:
>
>>> Why do step-start circuits in the primary of the HV transformer
>>> have two resistors and relay contacts shorting the resistors in EACH
>>> (i.e. BOTH) leads of the primary?
>
> seems to be...
>
>> So that it will work right on either 120v Or 240v mains.
>
> As Rich and others have pointed out.  But the two-resistor scheme has
> overflowed into the 240V only power supplies, probably due simply to
> "copying what worked fine last time."

I have built two 240v-only amplifiers, and I am slowly building a 
third,  All three use a SPST DC-coil stepstart relay and a single 
resistor.
>
> If one has a split primary or a dual primary transformer, then the
> two-resistor version is the way to go.  If it's a single primary, one
> is certainly adequate.

If it's a single V only amplifier, a single resistor will do the 
stepstart.  Dual-V amplifiers require two stepstart resistors
>
> 73,
>
> George T. Daughters, K6GT
>
>
>
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>

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org