The standard technique is a "corona ring"....so you avoid any sharp points
on the high voltage end of the wire and increase the radius....you remember
the brass balls on the end of Wilmshurst Machines :-)) All you need is a 4
to 6 inch circular loop of copper wire (stiff so self supporting) at the
insulator. Another piece across the diameter for mounting and connecting to
the end of the wire. The loop becomes the "end of the wire".

I have a feeling Jim wrote this up somewhere. Steve GW4ALG burst he support
balloons with the corona before he terminated the wire in a loop. It is a
significant loss of power at high power levels.

Alan G3NYK

----- Original Message ----- 
From: "Graham" <[email protected]>
To: <[email protected]>
Sent: Wednesday, March 02, 2011 8:32 PM
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 .