Wire length,resonance, and Q (correction]
From: Mark S Graalman [SMTP:wb8jkr-at-juno-dot-com]
Sent: Saturday, May 30, 1998 8:00 AM
Subject: Re: Wire length,resonance, and Q (fwd)
Oops, allow me to correct my post, current will
LEAD the voltage during the charging of Cterm.
On Fri, 29 May 1998 23:09:09 -0500 Tesla List <tesla-at-pupman-dot-com> writes:
>From: Mark S Graalman [SMTP:wb8jkr-at-juno-dot-com]
>Sent: Friday, May 29, 1998 5:00 AM
>Subject: Re: Wire length,resonance, and Q (fwd)
> Yes that's true Greg, but (lets see if say this right)
>looking at the charging of Cterm the current will lag
>the voltage by 90 degrees, Maximum I-term and
>Maximum E-term don't occur at the same time.
>I would think the phase relationship between the two
>would be much closer at the coil base.
>On Thu, 28 May 1998 23:36:05 -0500 Tesla List <tesla-at-pupman-dot-com>
>>From: Greg Leyh [SMTP:lod-at-pacbell-dot-net]
>>Sent: Thursday, May 28, 1998 7:17 AM
>>To: Tesla List
>>Subject: Re: Wire length,resonance, and Q (fwd)
>>Mark S Graalman wrote:
>>> I have to wonder here if there isn't a simple
>>> misunderstanding of 1/4 wave resonance, the fact
>>> that we are talking about an ELECTRICAL 1/4 wave
>>> and not a PHYSICAL 1/4 wave. That a 'monopole'
>>> tesla secondary is a ELECTRICAL 1/4 wave from
>>> the bottom to the top, and any situation where one
>>> has a current node at one end and a voltage node
>>> at the other is being operated as a 1/4 wave electrically
>>> regardless of its physical length.
>>This is true, and devices such as waveguide stubs and antennas
>>often operate in this 1/4 wave mode. However, a TC secondary
>>_does not_ behave in this way, for the following simple reason:
>>There is no actual voltage node (max V, min I) at the top.
>>Although there is a current node at the base (max I, min V),
>>the top winding carries both the maximum voltage _and_ nearly
>>the maximum current, just like in a standard HV transformer.
>>This current at the top simply goes into charging the top
>>electrode, which has a lumped capacitance back to ground.
>>The current going into the arc is typically only 30 to 40%
>>of the total current being delivered to the top electrode.
>>If you change the "electrical length" of the TC secondary,
>>this will still be the case.
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