> Some step-start circuit troubles have been reported recently.
>
> The step-start circuit usually seen can sometimes cause trouble; the
> problem is that the relay coil is part of the RC timing circuit. This
> means that as the capacitor charges it first reaches a point where the
> relay armature just begins to move slowly, and then finally the relay
> closes. Not a snap-action arrangement. This slow closing can cause
> contact burning and eventual failure.
>
It's been my approach that other than a minimum for each tube, the
timing is unimportant. IOW if the tube needs 300 ms, anything longer
than that within reason such as 3, or 4, or 5 seconds shouldn't make a
difference... except to the power dissipated in the soft start
resistor. OTOH the relay should not close slowly. The voltage should
be supplied to the relay coil as if it were being done by a "snap
action" switch.
73
Roger (K8RI)
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