[Amps] Corona

[PA3DUV]

WIth 500 watt into my HiQ 5-80 centerloaded vertical on my car the 2 mm diameter whip top was launching corona flames on 40 and 80 meters.
In order to run the Henry SS750 @ 1100 watt output into the HiQ 5-80 center loaded vertical I had to put a 1" aluminium coronal ball on top.
http://www.qsl.net/pa3duv/mobant.html

With 5000 watt carrrier on 80 meters into the 2 mm diameter copper wire of my 2 x 20 m center fed dipole no corona discharge could be observed.

Cheers, Dick
PA3DUV


  ----- Original Message ----- 
  From: Peter.Voelpel 
  To: g3rzp at g3rzp.wanadoo.co.uk ; pa3duv at planet.nl ; amps at contesting.com ; df3kv at t-online.de 
  Sent: Monday, January 02, 2006 6:31 PM
  Subject: Re: [Amps] How about this furnace?


  Hi Peter,

  yes, 3-phase supply into the house is standard for at least 20 years, you also find very few overhead power lines here, if, they are usually 3-phases as well.

  Concerning corona at Quito, that was a matter of altitude and 10KW.

  Your case is no corona but overload of components.
  Either you did something wrong on your matching network
  or the antenna is much to short which I guess with 20KV at 1KW.
  But you can easily produce corona when you base load a 30cm long radiator on 80m with 100W.
  Usually who runs high power has no shorted antennas with traps or coils anyway and then it should be no problem except on high altitudes.
  High power does indeed a big change to the electricity bill.
  When I ran with the linear on most times, my bill was 2000 Euro the year (for one person!), now with low power I educed it to 400 Euro only using the linear occassionally and that is far away from 20KW input.

  73
  Peter


  73
  Peter

  From: Peter Chadwick 
    >In a 3-phase environment which is standard nowadays in
    central Europe that is no problem at all, at 20KW input you
    need 28A per phase.<

    So guys, are you saying that on the Eu mainland, domestic properties are routinely provided with 3 phase mains?

    They certainly aren't in the UK, and as far as I'm aware, not as a matter of routine in the US. I suspect a request for installation in domestic properties would meet with some questions, especially with our new UK 'nanny state' electrical regulations. Even my neighbouring farm only has single phase in the farmhouses.

    The main supply to my house is fused at 100amps, (24kW at unity PF) although if you tried drawing that much, the voltage sag would hurt, as I'm on the end of the best part of 500 metres of overhead line from the transformer. It used be two phases from the transformer, but there's now 3 phases from a new transformer (it's fed from a an 11kV 3 phase overhead line) and two of them get to the pole outside my house. But only the neutral and 1 phase come in. To get 3 phases for the lathe and mill, I have a solid state inverter, although as it provides variable frequency, it provides variable speed, too.

    But the other point that needs considering in the current draw is the amplifier power factor. If that was 0.8, the current goes up by 1.25 times for the same power.

    And I still don't like the idea of the electricity bill!

    As far as corona is concerned, don't bet on it. The Quad originated at HCJB because 10kW led to corona off the ends of the Yagi they tried. Some locations you may get away with it, but I've seen problems with 1kW at 500kHz into a shorter than usual antenna. On my 80 and 160m vertical, I've been rebuilding the tuner since I changed the beam on top to a Steppir and reduced the capacitive loading. I had a beautiful blue glow inside my 500pF 15kV vacuum variable - does anyone rebuild or repump those? - and building padding capacitors witrh 0.064inch thick glass produced impressive fireworks and pinholes in the glass around the edges of the metal electrodes - and broken glass. That was with less than 1kW!!! A 7.5kV peak vacuum variable will just do it (I hope): for 10kW, I'd be talking in terms of 20kV plus at the antenna terminal......