Hi G dont get too complicated .....yet...... think the end of a bit of wire
1mm diam even if domed the radius of curvature is 0.5mm (but its prob been
cropped with cutters !). Now connect that to the centre of a disc of metal
with a smooth edge, 100mm in diam (that 4in for the decimally challenged
and OAPs like me :-)) ) the radius of curvature is 50mm 100 times greater so
the field is (probably 100 times) lower. It doeesnt matter its only 2D and
across the wire is still 0.5mm because you now have 30cms of that in
parallel.... the periphery of the ring. It might be better is the rings were
made of 5mm tube but that is lot heavier, you are not gaining much, and
discs and spheres have too high a windage. I dont think two rings are
necessary at our power levels a pair of binocs on a dark night should show
if you still have a problem.
Jim will put me right if I "balled" it up :-))
Alan
----- Original Message -----
From: "Graham" <[email protected]>
To: <[email protected]>
Sent: Wednesday, March 02, 2011 10:26 PM
Subject: Re: LF: Corona Discharge - how to prevent ?
Thanks Alan , John.
Yes that seems to be the solution , may be a ball would do the same
thing ?.. I was wrangling with the charge distribution angle .. as to the
best way , assuming a sharp point on the ring would still produce the
same corona ?
The double stacked ring looked a good idea , but is only in 'one
plane' what happens at 90 deg ie in front and behind ... ?
The tube has possibilities, I have some copper brake pipe , that should
do the job ....
Pity to quench it, it looks quite impressive in the night ! , (not
sure what its doing to the local
medium wave reception though...)
tnx - G..
From: Graham
Sent: Wednesday, March 02, 2011 8:32 PM
To: [email protected]
Subject: LF: Corona Discharge - how to prevent ?
Corona Discharge - how to prevent ?
Running into corona problems with a small loaded antenna ,
terminating as a wire at the far end
Q has any one addressed this problem and found a suitable solution ?
Apparently more prevalent on 136 khz , this is presenting on 500k , I
can find reference to rounded objects and rings , one being two sets
of ring's the second being insulated to reduce the v/mm stress , but
these where part of a high voltage insulator with the far end
earthed , not so in this case, the wire ends in free space ..
Increasing the surface area will distribute the charge , but will
not reduce the stress as this is a generated field as opposed to a
static build up ?
Links / ides ?
Tnx - Graham .
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