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New Coil Measurements



Hello everyone,
                Due to the lack of good _reliable_ caps I cannot 
undertake any repetitive firing (an absolute curse). BTW, would 
somebody please post the following information on Condenser Products:
phone number, fax number, full postal address? It is clear I'm going 
to have to try doing some kind of deal with the company due to the
additional expenditure sending caps hither and thither in a reasonable 
amount of time is going to entail (not to mention the headache of 
reversing customs charges etc etc.).
    
    However, I have done some characterization of my new resonator 
and done some single shot expts in less than ideal conditions (rotten 
isolation). FYI:

Reiterating : Ls = 162mH, Hs=39", Ds=16.8", Cs(Med)=23pF,
              Fr(projected)= 82kHz, n=1000 turns

Measured: Fr of bare resonator = 83kHz (Medhurst wins again), Q 
"unloaded" = 230 odd (this is with poor isolation and I didn't bother 
to check this with the topload). The resonator was mounted 16" off 
the floor to get these but the top was never more than a couple of 
feet from any object (sigh).

Interesting stuff: I dug out my 19" toroid (ring dia about 4.5"), 
Cisolated calc'd around 15pF. I have previously measured the 
capacitance at around 13 - 14pF above a much smaller coil. On this 
occasion, mounting about 3/4" abpve the windings yielded an 
_effective_ value of 4.5pF. Mounting it about 3" higher gave about 
6.3pF - not the most effective topload in history. It only overhangs 
the coil by an inch or so all round. At this setting, Fr = 73.1kHz.
Interesting to see how the mutual capacitance of a large resonator 
and small topload decimates topload effectiveness.

Fp     Cp     Lp     Ecp     k     Spark    Vo(35k/")  Vo(lumped)  

84.8k  50n   70.5u   2.7J   0.23     12"      420kV      429kV
68.8k  100n  57.4u    6J    0.17     19"      665kV      640kV
66.5k  200n  28.7u   8.1J   0.18     22"      770kV      743kV
71.7k  200n  25uH    11J    0.15     25"      875kV      866kV

Notes: - interesting correspondence between spark length based on 
35kV/" and theoretical lumped calc. This is almost certainly too high
as no losses in prim are taken into account. My guess is that 40kV/"
would be coming close. About 1 in 5 sparks formed a bright connected 
channel with a wooden beam, piece of metal or grounded wire at the 
distance stated (the coil is clearly demonstrated to be capable of 
the length). I did measure a single attached streamer of 26"+ at the 
highest energy. On 4/5 occasions, multiple streamers were heading off 
the toroid dispersing energy in different directions. A number of 
these exhibited clear forking.
       - k's are approximate (BW/F) and vary wildly due to primary 
coil combos used.
       - I didn't have enough Lp for the 50nF cap. All other Lp's 
gave the longest measured spark under these conditions.
       - The caps used were two of my dry-fired polyeth caps. Corona
losses in them would have reduced efficiency - I'll take the storage
scope home and capture the decrements to get an idea of I^2.R losses 
in the various primary cominations. I may be forced to use them in
repetitive operation with some microwave transformers to get my ozone 
fix, but I have a serious problem - where to fire the darn thing 
without setting something on fire. Arcs would almost certainly glue 
themselves to the roof even at 100Hz rep rate and set the building 
paper alight.
       - at Ecp = 15J, theoretical Vo around the million mark.

Hope this is some use to Greg and others,
Malcolm

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