** I use a minimum value of R that  when added to the transformer
primary R  does not exceed the mains circuitbreaker (or fuse) ampere
rating. For example, a Heath SB220 has 10A breakers and c. 2ohms of
primary R when wired for 240V. Thus, to limit inrushI to 10A, the
stepstart R needs be at least 22ohms total.. More R adds step time.
As stepstartR keeps increasing, at some point, the HV will stop rising
before it reaches the desired 60% level which closes the stepstart relay.
In other words, mo' is not always mo' betta.
 The typical delay time for a stepstart using a value of R that limits
inrushI to the circuitbreaker rating is a bit under 1second  which
is about the same time it takes for a thoriatedtungsten filament/cathode
to reach full emission.
cheerz, Peter
>
>Any ideas on what values to use for step start resistors? In the past, I've
>tended to choose a value from the available stock  something like 50 ohms,
>100 watts, which limits the surge current to just over 4 amps. I expect
>that a value such that the current won't exceed the full load primary
>current of the transformer is probably best, but any suggestions?
>
>(I'll probably still use what's available in my stock of vitreous enamelled
>wirewound resistors about 10 inches long and an 1 inch in diameter,
>though!)
>
>73
>
>Peter G3RZP
>
>
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