It appears to very difficult to create corona from reasonably
low-Q antenna structures at sea-level.
The highest Q antenna I have encountered at work,
a folded dipole for 5541 kHz made out of 6 mm diameter wire,
did not show any corona even when fed by 30 kW PEP.
73/
Karl-Arne
SM0AOM
----- Original Message -----
From: "PA3DUV" <pa3duv@planet.nl>
To: <amps@contesting.com>
Sent: Tuesday, January 03, 2006 10:43 AM
Subject: [Amps] Corona
> 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@g3rzp.wanadoo.co.uk ; pa3duv@planet.nl ; amps@contesting.com ;
> df3kv@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......
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