Re: Very high current ?
Your RF choke should not be in your tank circuit. It should be between
your xmfr and the spark gap. At 6 kw with .02 MFD you will averaging tank
circuit currents of around 500 amperes assuming your LC tank circuit is of
relatively low inductance. You want these heavy currents in your tank
circuit to generate a powerful magnetic field which links your secondary
coil. At 500 amps you should be running no less than 2 AWG welding cable.
Slip tygon tubing over it for additional insulation and use the proper lugs
for terminal with this size cable -- available at any local welding supply
shop. 10 AWG is way too small for the resonant current you are building
and will melt as you discovered. Worst yet, you are loosing a lot of
efficiency as undesireable heat in your tank circuit.
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Very high current ?
> Date: Saturday, January 23, 1999 8:19 PM
> Original Poster: Bert Hickman <bert.hickman-at-aquila-dot-com>
> Tesla List wrote:
> > Original Poster: "Paul Marshall" <klugmann-at-hotmail-dot-com>
> > Hi every one,
> > I seem to be having some really heavy currents in my tank circuit.
> > I'm running a 6" coil in my basement at close to 6 Kw. I power the coil
> > using a 14.4 Kv pole pig. My tank circuit capacitance is .026 Uf. The
> > gap is linear air cooled (9 gaps). The coil seems to be preforming
> > fairly well. The farthest object in the basement is 81" away. I get
> > to it and everything else in the basement. Metal screens which are
> > grounded protect all of vitals. Several weeks ago my RF choke melted.
> > was wound with 18 AWG. The PVC core even melted. Keep in mind the run
> > times have all been less than 15 sec. Last night I examined my tank
> > circuit caps. The connections to the terminals are wired with 10 AWG.
> > The insulation had melted off of the wires ! What is happening here ?
> > Has anyone else experienced this ? Can I put an Amp meter on the HV
> > and check the current ? Its a clip on type and I could mount it with
> > meter facing me.
> > Any suggestions will be greatly appreciated
> > paul m.
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> What did your protection circuit look like? Are you using any damping
> resistors in series with the chokes? Putting a clip on ammeter around
> the high voltage circuit will not allow you to measure the RF currents
> which are burning up your choke, and could damage your ammeter. Also,
> #10 AWG is too light for running at 6KW in your primary circuit. The RF
> current peaks in your primary circuit when your gap fires are probably
> several hundred amps - you need to beef up this wiring substantially.
> -- Bert --