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RFI
All,
[subject change from the toroid thread.]
> Friday night I built a 7" by 20" toroid. At first I would not break out,
> just christmas tree corona down to the strike rail, I raised the toroid
>higher above the secondary, then I had direct strikes to the strike rail
>and secondary flash over. I then reduced the coupling, retuned and achieved
> no breakout. I put a 1/2" ball 1" above the toroid edge to act as a breakout
>bump and have a single blue-purple 2.5' (eye guesstimate) air discharge.
>Unfortunately, I now have a TVI problem with my 1 neighbor that has a TV
>antennae instead of cable. Since my other neighbors that share the same
>power distribution point are not experience TVI (with a cable TV connection),
> I would say that the TVI is radiated rather than conducted.
I will eliminate this, because I am a Short Wave radio listener and
will not subject others to RFI that I would not tolerate.
My first object of inspection will be my ground system.
I'm using 20' of #6 cable to a single 8' ground rod. Between that rod
and my short wave antennae ground rod 40'ish away I measure 12.6 ohms
(-at-1kHz). I'm only 1.5 miles away from the San Francisco bay, the
normal brackish water is 12' below me. I've not checked my well to see
if the water level has risen after all the rain we've had. (my ground
rod may very well (npi) be in the salt water.)
(2 hours of coiling fun later)
I just used a NE2 on the ground cable and rod to check for HV. (Thanks
Father Tom for jogging my memory) I could not get the NE2 to light
with a 1 wire connection to my TC ground bar. I then connected a 3
watt neon lamp between the ground bar on my TC cart to the ground rod
to measure the voltage drop across the #6 ground wire. The 3 watt neon
would not light. A NE2 would light to full (outdoor shade) brilliance.
I then connected the NE2 between my TC ground rod and my short wave
antennae ground rod, I could just barely see any glow.
I remove the #6 cable and replaced it with 14' of #4 welding cable.
The NE2 would light only about 1/2 of one electrode. I had to get
close to the neon lamp to see this. Surprise only 1 electrode was
glowing! (see my post to: Explanation to the positive ES charge
thread)
I double checked my setup to make sure that the clip leads to the NE2
were not picking up the RF field from the TC by disconnecting their
far ends but otherwise not moving their positions. The NE2 did not
light. I concluded that I really was seeing a 90 volt drop across the
ground wire. This may be it. 90 volts across a 4 to 6 meter cable will
act as a GREAT antennae for 5mHz to 7mHz on up. (I used the 1/10
wavelength rule of thumb for RFI supression design here. To wit: any
conductor longer than a tenth of a wavelength will radiate.)
I don't have a battle ship to use as a ground, but the USS Hornet
(Apollo recovery Carrier) is docked 10 miles away. Just envision the
hanger: faraday shield, magnetic shield and salt water ground in 1;)