Re: CURSE Primary/ Grounded-centre or grounded edge?

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

Original poster: "Finn Hammer by way of Terry Fritz <twftesla-at-qwest-dot-net>" <f-h-at-c.dk>

Hello Scott!

comments interspersed.

Tesla list skriver:
> 
> Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<bigfoo39-at-telocity-dot-com>
> 
> Tesla list wrote:
> 
> >Original poster: "Jolyon Vater Cox by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <jolyon-at-vatercox.freeserve.co.uk>
> >
> >
> >Having seen photos of the CURSE primary, I am interested to know which
is the
> >better primary topology -the grounded-centre or the grounded-outer?
> >
> >I myself use a grounded-centre design and tap outwards to add more
turns, but
> >from what I have seen of the Danish coil photographs it appears that the
> >primary is connected at a point someway between the centre and the outer
> >primary turns to the base of the secondary through a number of small black
> >wires- are these grounded or not- also if the black wires are grounded
> where is
> >the "hot" end of the primary -at the inner or the outer turn?
> >
> >
> >
> >
> >
> I think I figured this one out....   those tubes I asked about in a
> previous post are the the supply to the center of the primary coil (
> which must feed thru holes in the base plate (( wires inside the 4
> tubes)) go over the primary to the center end). The center post is the
> "tap" source to the coil and the flat copper strip must be the feed thru
> to the tap source.  :)  TADA   ( im such a geeenyus )

This is correct. The wire is the inside of RG213, That means that I
strip the RG 213 wire off it`s jacket of black pvc and then it`s ground
sleeve. Inside is a nice thick 1/4 inch polyethylene insulated wire, 7
leads, 1mm thick. This is a kick a** cable!. ĪRuns next to each other is
sufficient to mimick a length of primary strip. Since it doesn`t cost
anything, and looks good, I try to maintain the conductive surface of
the primary circuit all along, even for the interconnects.
> 
> my new question...   why the multiple wire system to feed the primary ??
>    wouldnt one thicker wire be sufficient to feed the center of the
> primary and the tap??   or was this done to simulate a ribbon ( more
> surface area perhaps??) ??

Surface area is the key here, and in the frenzy thay I am in, when I
build, I couldn`t find the preferred wire for that job, twin lead
loudspeaker wire, so I made that bundle up off some 25 amps wire I had a
reel of. Surface area is the aim again here.
> 
> also ...   why wasnt the center post hooked directly to the source under
> the base plate thus removing the need for the copper ribbon on top of
> the base plate??

This is to bring that wire out of the way. On the underside of the white
table (which is 3/4 inch thick polyethylene) that wire would get in the
way. Routing it directly to abowe where it is needed makes things much
neater.
> 
> another thing...   the secondary RF ground is thin gaged wire ....
> seems that this is contrary to popular building techniques ( posts from
> the past have always told us to use heavy wire from the secondary base
> to the ground rod) ....    is this proof that we dont need a #0/2 RF
> ground wire ???  ;)

Only if the RF-Ground id a mere foot away! I would still have dragged
out my roll of 4 inch wide groundstrip material, if I had had to run it
for ant length, like a couple of meters. It makes a difference when you
have to run, say 10 metrers.
> 
> BUT   I still love this design

Thanks! I love the fact that you study it!
> 
> only thing I would change is the 4 tubes that cross over the primary....
>   I think I would use the front ( inside)  of one of the main supports
> to hold the coils center supply ( groove the support somehow insert
> wire) to get to the inner turn of the primary...

Just remember that the wires have to pass _over_ the primary to give
pure uncluttered access to the primary.....
> 
> Now     where do I find copper ribbon of sufficient size and length ;) 

Try yellow pages, and be prepared to pay some prize by weight. When you
call, rest assured that the price will be reasonable, don`t bargain,
unless that is part of the industrial culture around where you live. I
doubt ti is. Remember that industrial types are used to quoting prices
all day long, and that you gat goodwill, after you have made your first
purchase. Or go to them in person, strike up a conversation, show
pictures, perhaps they will give you the material for free or beer,
whatever.  ??
> 
> OHH    btw   Finn   where did you find that awesome motor mount for the
> SRSG ??

I made it myself, a couple of years ago.
Wanna see it when it was new?
http://wimshurst-dot-com/
> 
> kewl stuff ....
Even myself, I see it as craft-art.

Cheers, Finn Hammer
> 
> Scot D