Re: Ballasting OBITs

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "J. B. Weazle McCreath by way of Terry Fritz <twftesla-at-uswest-dot-net>" <weazle-at-hurontel.on.ca>

At 04:33 PM 25/01/01 -0700, you wrote:
>Original poster: "Hans Scholze by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <hanscs-at-eagle.ptialaska-dot-net>
>
>I have read many times that it is good to start at low power levels when
>first firing a new coil, but I don't have a variac.  I am using two OBITs in
>parallel, and I was thinking that I would just make a couple of ballasts for
>1/4, 1/2, and 3/4 power.  Is this necessary, or would just half-power be
>sufficient?  On my previous coil the only power control was seperation of
>plug and outlet, but I don't want to destroy my new one as I have put much
>more time and money into it.  I have a few OBITs with bad secondaries and I
>thought that if I put one of these in series with each good one, the power
>would be half.  Is this correct, or do the secondaries need to be shorted
>for a reasonable ammount of current to flow?
>
>Thanks for your help,
>Hans
>
>

Hello Hans,

Since your two OBITs will draw about 500 watts, you could put a small
space heater element of similar rating in series with the power feed
to give you half power.  In a pinch even a 500 watt light bulb would
give you some limiting, but it's cold resistance is low so the surge
current at initial power up would still be high until the bulb had a
chance to warm and increase its resistance.


73, Weazle, VE3EAR/VE3WZL

Listening: 147.030+ and 442.075+
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