I would think that you want the counterpoise directly around and under the TC to serve as the other capacitor plate.
I think welding cable is very wasteful because of the frequencies (around 75 khz) involved. The skin depth at these frequencies is only a few thousands of an inch. All that copper in the welding cable deeper than that is not used and is wasted. Better to use thin wide copper strip or wide copper braid. I use copper braid for the flexibility.
----- Original Message -----
From: "Yurtle Turtle via Tesla" <tesla@xxxxxxxxxx>
To: "Carl Noggle" <cn8@xxxxxxx>, "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, August 11, 2017 9:54:21 AM
Subject: Re: [TCML] First coil
Does a counterpoise work best directly under the coil, or could it be buried 10' feet away, but a HUGE welding cable to connect it?
From: Carl Noggle <cn8@xxxxxxx>
To: Yurtle Turtle <yurtle_t@xxxxxxxxx>; Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Friday, August 11, 2017 10:50 AM
Subject: Re: [TCML] First coil
A long wire or rod buried in a horizontal trench often makes a better
ground than a vertical rod, especially when there is caliche or rocks
that prevent digging deep holes. The good thing about a Tesla coil is
its high impedance, so it can tolerate a high impedance ground. I have
used a screwdriver pushed into the ground, and it worked well. You can
pour some water into a depression around the screwdriver. (Cheesy but
effective)
Safety ground for the power supply should, of course, return to the
service entrance (green wire) and be separate from the secondary low end
ground.
--- Carl
On 8/11/2017 1:30 AM, Yurtle Turtle via Tesla wrote:
> Nice work. Are your ballast laminations individually coated?
>
> From: Chip Atkinson <chip@xxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Sent: Thursday, August 10, 2017 11:59 PM
> Subject: Re: [TCML] First coil
>
> Hi Steve,
>
> I put the pictures that you sent up on pupman.com.
> http://www.pupman.com/current/swhite/index.html
>
> My fancy thumbnail generating script got lost in the server move a long
> time ago, so it's just file names.
>
> Chip
>
> On Thu, 10 Aug 2017, Steve White wrote:
>
>> I just completed my first tesla coil. It is a large one. Here are the prime specs.
>>
>> * 8.6" secondary with 1410 turns
>> * 8 x 10 toroid
>> * Center line of toroid is 71" above ground plane as defined by javatc
>> * 12-turn primary currently tapped at turn 10.5 ( all primary circuit "wiring" is done with 3/8" copper tubing)
>> * 45 nf of capacitance using 6 Maxwell energy discharge capacitors in a series-parallel configuration with load balancing resistors
>> * 10 kva pole pig running at 14,400 volts
>> * Sophisticated control cabinet including 25-amp variac, ballast, RSG phase control, breakers, contactor, PFC capacitors (currently about 150 uf), volt meters, current meters, EMI filters, MOVs, lockout switches, indicator lamps
>> * Hand-made ballast with adjustable air gap currently set for 20 amps (similar to Richie Burnett's)
>> * Rotary spark gap with one stationary 5/16" tunsten electrode and 4 flying 1/8" tungsten electrodes turning at 3600 RPM
>> * HV leads made from 10,000 volt AC Belden test lead wire threaded through PVC tubing for additional insulation. This is all surrounded by grounded copper braid for uniform field distribution and to protect against streamer strikes.
>>
>> I made extensive use of javatc to design this coil. I was confident in starting with a large coil because I am a retired electrical engineer thus I had a lot of knowledge about electrical theory. I also own my own mill, lathe, bandsaw, oscilloscope, and signal generator. Finally, I had the funds to muy and/or build quality parts.
>>
>> Even though this was my first coil, surprisingly it worked the first time that I fired it up. I am currently getting 6.5 foot power arcs. It should be getting up to about 8 feet according to javatc. I am continuing to adjust the primary tuning. I think I need to go a little lower in frequency to account for streamer capacitance.
>>
>> I do have a few questions concerning RF grounding. I currently have a copper-clad steel rod driven 3 feet into the ground for the RF ground. This is as deep as I could drive it. I may try a water boring rod to try and get deeper. I currently have the following connected to the RF ground.
>>
>> * Strike rail
>> * RSG motor chassis
>> * Copper braid shield around HV leads
>> * Copper braid around RSG power cord
>> * Pole pig case
>>
>> Does this sound about right?
>>
>> Steve White
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxx
>> http://www.pupman.com/mailman/listinfo/tesla
>>
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>
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>
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