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RE: Tuning and Performance Questions (6.5" coil)

Chip,

Major changes in the toroid height definitely affect the tuning.  But, the
small .5" change I'm making isn't perceptible as far as tuning goes.

I hope to do some more coiling this weekend if other stuff in the house
quits breaking. 

On Thursday I'll put some of my Halloween pictures up on my Web site.

Regards,
Brian D. Basura



-----Original Message-----
From: Tesla List [mailto:tesla-at-pupman-dot-com]
Sent: Monday, November 02, 1998 9:55 PM
To: tesla-at-pupman-dot-com
Subject: Re: Tuning and Performance Questions (6.5" coil)


Original Poster: Chip Atkinson <chip-at-pupman-dot-com> 

Brian,

Your performance sounds pretty good to me.  It seems to me that your
safety gap spacing is a bit conservative, but then again I just toasted
two caps :-)

Does the height of the toroid change the tune at all?  You said that your
performance dropped, but could that have been due to tuning?  

Chip

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 Chip Atkinson 
 http://www.pupman-dot-com 
 --- If I can't fix it, I can fix it so it can't be fixed --
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

On Mon, 2 Nov 1998, Tesla List wrote:

> Original Poster: "Basura, Brian" <brian.basura-at-unistudios-dot-com> 
> 
> Hello,
> 
> I've been tuning my 6.5" coil and have reached a new personal best of
> consistent 60" strikes to a grounded rod with 1.6kva input.
> 
> I have two questions/concerns:
> 
> 1) Toroid height affects my coil operation dramatically.  Not just spark
> length but consistency and smoothness of operation. With the toroid set at
> it's current height above the secondary, I get a faint purple corona from
> the top of the secondary down to the strike rail.  Is this OK? If I raise
> the toroid 1/2" I get breakout from the top turns of the secondary.
> Lowering the toroid 1/2" destroys performance.
> 
> 2) My capacitor bank consists of four rolled poly caps in a
parallel/series
> arrangement for a total of .042mfd with a total dielectric thickness of
> .072" (spread over two capacitors).  I also have a safety gap across the
> capacitor bank.  It's made of two 1/4" stove bolts with their heads facing
> each other and a gap of .3"  When the system is in tune my safety gap
starts
> to fire whenever my variac voltage gets to 100v (when out of tune it fires
> much sooner).  Am I being too conservative with this gap?
> 
> 3) Performance was in the 34-36" range until the last marathon tuning
> session where I did a lot of work on toroid height and fine tuning of the
> tap.  I now achieve consistent 60" strikes.  Is this good performance for
> 1.6kva into the system or should I look for more?
> 
> Settings:
> 
> Current limited to 17amps using three MOT's (with shorted secondaries) and
> 6.2 ohms (all in parallel).
> Maximum Variac setting is 95volts
> Primary Tap is at 7-5/8 turns
> Spark Gap is RQ type (with a blower) using five gaps for .150"
> Secondary windings start .5" above the primary
> Toroid is 4.5" above the top secondary winding
> 
> Coil specifications are as follows:
> 
> Primary Transformer
> Input Voltage		95 VAC
> Input Current		17 Amps
> Output Voltage		12,000 VAC (-at-120v in)
> Input frequency		60 HZ
> 
> Primary Design
> Inside Diameter		9.5 inches
> Average Radius		8.88 inches
> Wire Diameter		.025 inches
> Total Diameter		26.0 inches
> Wire Spacing		0.25 inches
> Wire Length		79.0 feet
> Total Turns		17.0
> Secondary Res. Freq.	124.2 khz
> Inductance		0.1407 mh
> Primary Cap to Res.	0.0117 uF
> Angle of Windings	0.0 degrees
> 
> Secondary Design
> Diameter		6.50 inches
> Radius			3.25 inches
> Winding Length		27.5 inches
> Circumference		20.42 inches
> Wire Gauge		22 awg
> Wire Length		1698 feet
> Turns per Inch		37.4
> H/D Aspect		4.23
> Inductance		34.56 mh
> Resonate Frequency	248.1 khz
> Medhurst_K		0.72
> Res. Freq. w/Toroid	130 khz
> Self_C			11.91 pf
> 
> Top Load
> Type			Direr Duct Toroid
> Size			6" chord x 30" diameter
> Top Load C		32.1pf
> 
> Tank Capacitors
> Number of Capacitors	4
> Capacitor Configuration	Series/Parallel
> Type			Rolled LDPE
> Overall C		.042 uf
> C of each unit		.042 uf
> Dielectric Constant	2.0
> Plate Length		120 inches
> Plate Width		14 inches
> Dielectric		.036 inches (6-at-.006")
> 
> 
> Pictures available at the following:
> http://www2.hughes-dot-net/~brianb/teslahome.html
> 
> Thanks in advance (hope this isn't too much information)
> Brian D. Basura
> 
>