Resonant charging

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


Hello Coilers,

Over the weekend I spent conciderable time reading through an old book
titled "Handbook of Technical Instruction for Wireless Telegraphists"
which was given to me by a friend who had been a radio operator aboard
ships back in the spark days.  I found a chapter of it interesting and
I wanted to share it with the rest of you.

During the description of a typical spark transmitter, which seems to
be similar to a Tesla coil in many ways, they describe each component
of the system and its role in it.  One such component was the inductor
that was wired in series with the primary of the power transformer as
we do with our ballasts.  The difference was that they used the choke
to tune the low frequency (70 Hz.) circuit to resonance with the tank
capacitor in order to achieve the highest voltage charge in the cap.

The power transformers they used had a turns ratio of 1:300, whereas
our NSTs and OBITs are 1:100, meaning they must have been getting a
very high secondary voltage in a resonant condition.  I'm surprised
that the plate glass caps that they where using in those days could
stand that sort of strain.  The whole thing seems to go against our
policy of trying to avoid a resonant condition, unless under special
conditions like Gregg's D.C. resonant charging for instance.

I will be interested, as I'm sure other coilers will too, in hearing
comments on this setup from some of you more knowledgable chaps on
the Tesla list. 

73, Weazle, VE3EAR/VE3WZL
G-1#1214

Listening: 147.030+ and 442.075+
E-mail:    weazle-at-hurontel.on.ca
           or ve3ear-at-rac.ca
Web site:  http://www.hurontel.on.ca/~weazle