Re: OLTC update - Poor seconadry Q

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Jimmy,

On 30 Aug 2002, at 20:54, Tesla list wrote:

> Original poster: "jimmy hynes by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<chunkyboy86-at-yahoo-dot-com>
> 
> 
> how do you know the q is so bad? did you measure it or calculate it? can you
> feel the secondary heating? also weak compared to other 300 watt coils
you have
> made or seen or are you comparing it to johns formula for input power and
park
> length? the formula might not be accurate at low powers, i doubt he looked at
> alot of 300 watt coils when making the formula. my calculations said the q
> should be around 200. i used the javatc to get a guess at the resistance. i
> dont trust my calculations too much because i didnt find the equations. i
> derived the equation myself, and i make alot of mistakes. 

I could see it just by looking at the oscillogram of the secondary 
ringing alone. A decent secondary rings for ages. It basically stands 
to reason. If you use thin wire and a long length of it in a 
relatively small coil, the AC losses will be, to use the Corum's 
words, incredible. Been there, done that. Obviously, the wire is far 
smaller than even a single skin depth at the frequency Terry is 
running and the proximity losses make it even worse.

Regards,
Malcolm


 
> Tesla list wrote: 
> >
> > Original poster: "Terry Fritz" 
> >
> > Hi All,
> >
> > I have adjusted my coil as best I can but the output still seems "weak". I
> > think I now know why. My secondary Q is only 36. That works out to a
> > secondary AC resistance of about 3300 ohms!! R = 2 x pi x F x L / Q
> >
> > Paul - The pinger file is here if your are interested.
> >
> > http://hot-streamer-dot-com/temp/OLTCsec.CSV
> >
> > The waveform is at:
> >
> > http://hot-streamer-dot-com/temp/OLTC08-30-01.gif
> >
> > Just to give an idea of how bad this is... I am pumping and quenching 317
> > watts into the secondary system. 53 watts is going to streamers and a
> > stunning 264 watts is going into heating up the secondary!!!
> >
> > So 83 percent of the power is "lost" :-((
> >
> > Some notes are at:
> >
> > http://hot-streamer-dot-com/temp/OLTCnotes.txt
> >
> > The entries at the last tell of the Q=36 case.
> >
> > So... I don't k! now if it is the SonoTube, surroundings, proximity
effects,
> > plastic wrap coating... Have to test some things... A small chance it
> > could be the anti-parallel diodes...
> >
> > Of course, this is not a problem with the basic OLTC technology, that works
> > great!, but rather an age old problem of making secondaries without really
> > low Q...
> >
> > Of course, ideas on how I can fix this are more than welcome :-)) 
> >
> > The specs of the secondary system are:
> >
> > L = 480mH
> > Wire gauge = #28
> > Turns = 2760
> > Winding length = 41 inches
> > Diameter = 10.75 inches
> > Q = 36.0 :-p
> > Fo = 38.2kHz
> > Csec = 35pF
> >
> > Torroid 24" diameter x 6.5" cord 
> > Center or toroid 3.5 inches above last secondary turn.
> >
> > Cheers,
> >
> > Terry
> >
> >
> 
> 
> 
> JImmy
>