Re: LTR question

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Mddeming-at-aol-dot-com>

In a message dated 10/27/01 11:50:21 AM Eastern Daylight Time, tesla-at-pupman-dot-com
writes: 



>
> Original poster: "Steve White by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <slwhite-at-zeus.ia-dot-net> 
>
> I have been reading a lot of posts lately about LTR (lower than resonant) 
> capacitors. This term does not make sense to me. Any capacitor in combination
>
> with an inductor will form a tank circuit which will resonate at a frequency 
> determined by the values of the L and C. Is LTR refering to some sort of 
> stagger tuning where the primary tank circuit is resonant at a slightly 
> different frequency than the secondary tank circuit? If so, to what end? In 
> either case, a common suggestion that is offered to achieve this "LTR" is to 
> use a slightly smaller or larger capacitor than one would normally use. The 
> same result could be achieved by merely changing the tap position on the 
> primary inductor rather than going to the trouble of changing the capacitor. 
> Another reason often cited for using this "LTR" value of capacitance is that
> it 
> lowers the peak voltage that the capacitor is exposed to. This does not make 
> sense to me either. The resonant frequency of the tank circuit should have 
> little effect on the voltage passing through the tank circuit. If stagger 
> tuning is being referred to, then there may be some rationale here. Any 
> insights? 
>
>



Hi Steve, 
The confusion results from the fact that the cap is resonant with two different
coils. 
1. It resonates with the primary coil of the TC to produce the HV RF energy. 
2. BUT it also has a resonance with the secondary of the NST (or other
transformer) It is THIS resonance at ~50-60 Hz that the term LTR refers to. It
is the ~60Hz resonant rise that will kill your power supply, caps, etc. 

Hope this clears it up, 

Matt D.