From:  D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
Sent:  Monday, June 15, 1998 11:31 AM
To:  Tesla List
Subject:  Re: interference

to: Julian

Corcom makes good 20 amp 220 volt filters.  Don't operate without them or
your neighbors will hate you -- or report you and start the up trouble. 
You can get used filters from Fair Radio Sales, Lima, OH, for a reasonable


> From:  Julian Green [SMTP:julian-at-kbss.bt.co.uk]
> Sent:  Sunday, June 14, 1998 6:24 AM
> To:  tesla-at-pupman-dot-com
> Subject:  Re: interference
> > From:  D.C. Cox [SMTP:DR.RESONANCE-at-next-wave-dot-net]
> > Sent:  Friday, June 12, 1998 12:40 PM
> > To:  Tesla List
> > Subject:  Re: interference
> > 
> > to: Julian
> > 
> > You should run a pair of commercial RF filters in series -- 2 stage EMI
> > supression.  Also a 1 1/2 size ferrite toroid with aprox 2 turns on
> > leg of your power wires (hot and neutral) will help reduce any
> > RF.  It's also a good idea to use a few varisters from each line to
> > at the xmfr input power points.  This along with a 1 K, 50 watt
> > off each xmfr bushing will help to keep RF kickback into the power
lines at
> > a minimum.  
> At present I dont use EMI supression units - I couldnt find anything
> enough.   My coil is pole pig powered and draws 13-15 amps when running. 
> have no PFC caps either.
> I was hoping that the 100meter extension lead that I use to power the pig
> would act as RF supression and balast.   A coiled externsion lead looks
> this (I think):
>  Live   >---OOOOOOOO--->
>             --------      Load
>             --------
> Neutral >---OOOOOOOO--->
> and has a DC resistance of 5 Ohms.   I see this circuit printed on the
> of RFI supression units.   
> The radio walk test was conducted with the coil running at a 'safe' power
> level and no streamers.   The radio was tuned to 200KHz (same as my
> I walked roughly 50feet and the interference on the radio stopped - this 
> supprised me as I thought I had a long walk ahead of me.   When the coil
> running with no spark breakout there is little or no interference on TV 
> reception.
> >From the above tests do you think that the coiled extension lead is
> OK, or should I setup better RFI supression?
> I also have a question about PFC - how do you calculate/guestimate the
> of the cap needed?  (If I power up the pole pig with primary cap
connected and
> spark gap open the pole pig is drawing 4Amps.  Its a 5KVA unit 240V -
> > Don't forget to invite your neighbors over for a free BBQ
> > sometime soon -- if they understand what you are doing and think your
> > is "cool" they are not so likely to think of you as a "geek" whose sole
> > intent is to destroy their TV reception while they are watching their
> > favorite prime time shows -- and be sure to find out when they watch
> > most and don't run during those times.  Trying hard to be a "good
> > with an interesting hobby" goes a long way towards reducing the
> > neighborhood pest syndrome.
> > 
> > DR.RESONANCE-at-next-wave-dot-net
> > 
> > 
> Tried that - no joy.   More 2am coiling for me then.
> Julian Green