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Re: Double humpin'
Tesla List wrote:
>
> > Subject: Double humpin'
>
> >From bert.hickman-at-aquila-dot-comWed Nov 6 22:38:16 1996
> Date: Wed, 06 Nov 1996 22:41:18 -0800
> From: Bert Hickman <bert.hickman-at-aquila-dot-com>
> To: tesla-at-pupman-dot-com
> Cc: Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject: Re: Double humpin'
>
> Tesla List wrote:
> >
> > >From hullr-at-whitlock-dot-comTue Nov 5 22:17:31 1996
> > Date: Tue, 05 Nov 1996 10:37:59 -0800
> > From: Richard Hull <hullr-at-whitlock-dot-com>
> > To: tesla-at-pupman-dot-com
> > Subject: Double humpin'
> >
> > All,
> >
> > I get the impression that some of our folks think that you get a double
> > hump or spliting of frequencies at tight coupling. Double humping only
> > occurs in spark systems when we exceed the point known as "critical
> > coupling". critical coupling has only a little to do with
> > actual inductive coupling (about 50%)
> >
> > If we throw a fixed gap of a fixed dwell/quench in a system, critcal
> > coupling occurs at some fixed coupling coefficient K=X. If we have a
> > variable dwell/quench gap, and a fixed tight coupling, by varying the
> > dwell we can make the system go from below critical coupling to well
> > beyond. In short, critical coupling is a sliding point based on actual
> > inductive coupling and dwell/quench time of the gap's realizable
> > quenching ability. In theory we can have a single frequency output (no
> > splitting) at k=.65. This was the struggle in the early days of spark
> > transmitters in the 100KW-.5MW class.
> >
> > Richard Hull,TCBOR
>
> Richard,
>
> Excellent point Richard! Seems like every time I think I'm beginning to
> understand how these things work, mother nature, or you, slap me upside
> the head with a dose of reality!
>
> A lot of coilers, myself included, have _lousy_ gaps which quench poorly
> and non-repeatably. With longer-than-desired quench-times, most of us
> seldom observe the phenomenon you describe! I needed to do a series of
> PSPICE simulations to confirm this - I have NOT been able to confirm it
> experimentally, since I don't have my high-speed rotary constructed as
> yet (a Winter project...).
>
> The PSPICE simulation shows that, if the gap dwell-time is reduced to
> the ideal time or somewhat less (i.e., the end of the first beat IF the
> gap were to continue firing), the double frequency humps do, indeed,
> disappear! Even if the primary is set to a somewhat lower frequency, the
> secondary/toriod will ring up at its single natural frequency ONLY.
That is very gratifying and a real world WIN for PSPICE to predict what I
have observed for a few years now. By the way this was understood by
many engineers in the early 1900s as they dinked around with spark
systems in the near megawatt RMS input class! R. Hull
>
> This seems to imply that frequency splitting and secondary coil
> flashover _could_ be reduced by consistently quenching quickly enough.
> Previously I believed that secondary flashover was caoused by the
> secondary being driven to the upper "hump" frequency, which in turn
> caused the 1/4 Wave point to be lower on the coil. NOW, I'm no longer
> sure that this is actually the case! Or maybe splitting only occurs
> during subsequent beats (at lower energy??), but this doesn't sound
> right either!! Hmmmm!! What seemed to be so simple before, turns out now
> to be another layer to peel on the TC onion!
>
> Thanks again for a very thought provoking post, Richard!
>
> Safe coilin' to ya!
>
> -- Bert --