Re: secondary coils for tube coils (fwd)
---------- Forwarded message ----------
Date: Thu, 21 May 1998 22:46:37 +0200
From: Pete <casius-at-cyberserv.co.za>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: secondary coils for tube coils (fwd)
Hi again John,
Now I'm being a pest. Would it be asking too much for info on pusling tube
coils. Maybe I can put the NL5557's to good work.
My 1st tube coil used a 3.5"x10.5" secondary and a 6146 tetrode. Was rather
complex. I then built a 813 unit using the same coil. Was also too complex.
Next I used the same coil in my 3x812AW coil. got +/- 120mm discharge. I then
took the coil from my 12/30 NST unit and used it in the 812 unit. This coil is
4" x 19" with 24 gauge wire. Got a better responce - +/-160mm discharge. Will
wind a new 4"x25" coil for my 833 unit.
Tesla List wrote:
> ---------- Forwarded message ----------
> Date: Wed, 20 May 1998 11:24:47 EDT
> From: FutureT <FutureT-at-aol-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: secondary coils for tube coils
> In a message dated 98-05-19 16:27:43 EDT, you write:
> > I would be very grateful if someone can explain to me why a convensional
> > coil uses a height to diameter ratio of 3:1 upto 5:1 and most vacuum
> > tube coils I have seen use very long thin secondaries. I have a 3.5" x
> > 10" secondary powered by three 812AW triods. I get a 4" "brush"
> > discharge. Will I get better perfprmance if I went to a secondary say
> > 2" diameter by 36" long.
> > Regards
> > Pete >>
> Pete, all,
> The thin secondary design does not offer any advantages,
> and has the disadvantage of low Q. Perhaps the early designers of
> these coils paid too much attention to the turns ratio.
> The only way to substantially increase the output spark length
> is to increase the input power, assuming the coil is well tuned, etc.
> Vacuum tube TC's have been relatively ignored over the years, due
> to their power-hungrey nature and flamelike sparks. I use methods
> of pulsing my tube coils for better "efficiency", and a more interesting
> spark appearance and sound, IMO.
> John Freau