Re: HF sparks

From: 	richard hull[SMTP:rhull-at-richmond.infi-dot-net]
Sent: 	Thursday, July 31, 1997 8:38 PM
To: 	Tesla List
Subject: 	Re: HF sparks

At 08:30 AM 7/31/97 -0500, you wrote:
>From: 	Peter Electric[SMTP:elekessy-at-macquarie.matra-dot-com.au]
>Reply To: 	elekessy-at-macquarie.matra-dot-com.au
>Sent: 	Thursday, July 31, 1997 7:18 AM
>To: 	Tesla List
>Subject: 	Re: HF sparks
>> All,
>> High frequency systems just typically have worse sparks due to a number of
>> problems.
>> 1. dielectric losses are higher at high frequency
>> 2. Coronal losses appear higher
>> 3. small capacitors in HF systems mean lower power and less brilliance in
>> any sparks thus produced.
>> 4. smaller capacities in the terminals limit spark length and color
>> It is hard to conceive of a 2 mhz coil system spouting 5 foot white hot arcs
>> using normal Telsa coil construction methods.
>> In general, most coils under 500 khz are in the toilet spark wise due to a
>> any or all of the above reasons.
>> I think the argument offered about the higher frequency, higher energy
>> between 500khz and say 2mhz is just not a real item of concern where real
>> sparks are made and show just how fine hairs are being split on non-issues.
>> Richard Hull, TCBOR
>>From my own observations so far and from other peoples posts I am
>inclined to agree with all of your points except number 3. In the past,
>folk seemed to have built Tc's using the clasic formula for Capacitance
>vs input power and these have have been good performers. Recently
>though, Bert pool and others seem to have been using relatively small
>caps with higher break rates and getting very impressive results.
>Maybe not quite in the same league but I have recently re-fitted my 3
>1/2" 15KV 60Ma TC with a .01uF cap after blowing up my .015uF earlier.
>After re-tuning the primary, the forced air gap seems to fire faster but
>the length or appearance of the sparks seems to be the same (about 30"
>with my present  20" by 8" toroid).
>I am about to wind a new 6" secondary and I intend to leave all other
>parameters the same so it will be interesting to see if the lower freq.
>produces a longer spark?
>Cheers, Peter E.


If anything the TCBOR and I have championed small capacitors in systems!!!
We were using .012 caps in 8 KW maggey systems getting 8 foot white hot
arcs years ago.  Bert and others are just dicovering the value of this tack
on their own.

Point #3 above was meant to say that high frequency systems (1mhz and above)
can't use big capacitors  period!!!!  Think about the primary needed to
resonate a .12ufd capacitor at 1.5 mhz and you will see what I mean.

Richard Hull, TCBOR