[Prev][Next][Index][Thread]
interference
----------
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 each
> leg of your power wires (hot and neutral) will help reduce any additional
> RF. It's also a good idea to use a few varisters from each line to ground
> at the xmfr input power points. This along with a 1 K, 50 watt resistor
> 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 large
enough. My coil is pole pig powered and draws 13-15 amps when running. I
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 like
this (I think):
Live >---OOOOOOOO--->
-------- Load
--------
Neutral >---OOOOOOOO--->
and has a DC resistance of 5 Ohms. I see this circuit printed on the side
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 coil).
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 is
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 doing
OK, or should I setup better RFI supression?
I also have a question about PFC - how do you calculate/guestimate the value
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 - 11Kv)
> Don't forget to invite your neighbors over for a free BBQ
> sometime soon -- if they understand what you are doing and think your work
> 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 the
> most and don't run during those times. Trying hard to be a "good neighbor
> 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