[Prev][Next][Index][Thread]

RE: CAP DESIGN

 * Originally By: Kukkonen-at-snakemail.hut.fi
 * Originally To: Richard Quick
 * Originally Re: RE: CAP DESIGN
 * Original Area: UUCPE-Mail
 * Forwarded by : Blue Wave v2.12


On Fri, 30 Dec 1994, Richard Quick wrote:

> for the initial power up (a common practice). The coil would over
> couple rather badly with a small discharger, but this can be
> easily resolved by rasing the secondary coil up in relation to
> the primary coil (for example placing some plastic blocks under
> the secondary to lift it up, thereby loosening the coupling).

Yes - and with the large toroid the first turns of both coils
are at about the same level in your tuned coil-system?

> One of my best primaries for 4" and 6" coils was measured with a
> slope of 27 degrees.

Ok, I'll try to make it like that.

> That would be about right. Remember that the rating is in DC
> voltage, I came up with .0007 microFarads (uF) at 120kV.  

which does equal 700pF..

Apparently the capasitance can be somewhat lower but should not
be larger?

> then you would divide the capacitance into two parts (use less
> that 50% of the total) and place an equal capacitance between
> each HV line and the system (RF) ground. I have cautioned this

You are talking about the bypass-caps, right? The main capasitor
is placed parallel to the x-former - or should it be balansed as
well (equidrive circuit?) ?

> If I am converting these numbers correctly these toroid-ferrites
> are fine. It is unfortunate that all of my coiling relationships
> are calibrated in my head in USA measurements. In this respect I
> really feel "handicapped"! 

Don't worry - I do feel about the same about US units :)

About the ferrites : if memory serves, one should indeed use
ferrites - not iron cores - to get rid of rfi, as iron-core chokes
pass the rf through them like the ferrites pass 50Hz through..

About the caps:
I really can't find 60mil (or thicker) ld-PE here in Finland - it is 
definitely not manufactured in Finland and not used for anything :( - the 
companies I contacted even stated that it is impossible to make ld-pe 
foil that thick.. Well - I do could get .2 mm thick foil and use 8 
layers of it to get 1.6 mm which equals about 60mil=1.52mm - would this 
do? 

I could get some 2 mm thick hdpe but it would not be transparent and
thus have "adulterants".. Do you think this would do for a stacked cap?

btw: I just got a nice idea for the secondary - how about making the
tube by laminating polyester-resin on some mould and then winding
the coil on the polyester-tube and finally casting a few layers of
polyester-resin on the coil? This way one could make the walls as
thick (thin) as one would like to..

ps. I put your file about the experiments with electrical counterspoises
etc. to the ftp site last night.


Yours,

  Kristian Ukkonen.

___ Blue Wave/QWK v2.12