Re: All who know VTTC stuff ;-). (fwd)

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

Original poster: Kreso Bukvic <kreso.bukvic-at-kc.htnet.hr> 

Ok here you can see the old look and how im rebulding the coil.

http://free-kc.htnet.hr/Kreso-Bukvic/Teslin%20transformator%20s%20vakumskom%
20cijevi.htm

  It maked 20 cm sparks not 20 inch ( i wish it would).

I do not know what should get red in this tube.

Well anyway im thinking my secondary has a diameter of 7 cm and my last
primary had a diameter of 17 cm. Im thinking to resize my primary to 11 cm?

Higher coupling, maybe better sparks?

Looks like my tank casp is to smal but we will se.

Well anyway would it help to use samller primary?
Best Regards

Kreso Bukvic
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, July 20, 2004 2:38 AM
Subject: Re: All who know VTTC stuff ;-). (fwd)


 > Original poster: FutureT-at-aol-dot-com
 >
 > In a message dated 7/19/04 6:43:19 PM Eastern Daylight Time,
 > tesla-at-pupman-dot-com writes:
 >
 > >Im really sory. The shematics will be on my server soon, but here are the
 > >"specs", i remowed the feedback winding because i will rebuild this coil
i
 > >think it was a crap.
 > >
 > >Secondary
 > >Diameter: 70 mm
 > >Winding: 1000 turns of 0.4 mm wire
 >
 >
 > This is approximately 26awg wire.  such wire works well at least up
 > to a 40" spark.  I used 28 wire (which is thinner) for my 40"spark VTTC.
 > 70mm is almost 3" so that's OK too.
 >
 >
 > >Primary
 > >22 turns of 1 mm wire
 >
 >
 > Sounds like you're using about 2kV with level shifting for
 > 4KVAC or so?  That's good, but the primary wire is kind of
 > thin if your sparks are 20" long or so.  I forget how long they are.
 > It would be good to have wire that is at least 2mm thick.
 >
 >
 > >Feedback
 > >24 turns of 0.63 mm wire
 >
 >
 > This is OK.  The feedback coil does not handle much power.
 >
 >
 > >Tube - QB 3.5 - 750 tetrode
 > >Tube used as triode ( screen and grid connected together)
 >
 >
 > I'm not familiar with the specs of this tube.  But if it has a graphite
 > plate then it is probably robust.  It would be helpful to know the
 > specs of this tube.  Of course some tubes can be run with more
 > power than the specs would suggest.
 >
 >
 > >Filament transformer 5 V 30 A ( it has writing " Property of coherent
 > >radiation laboratories California - anybody ever hear for them?)
 >
 >
 > Never heard of them, but it is fine.
 >
 >
 > >PSU
 > >Mot with shunts, 2 uF cap and a diode affocurse
 >
 >
 > Is the MOT similar to USA/Japanese type MOT's?  about 600 to
 > 800 watt rated at 2kV or so?
 >
 > >Power controled by variac and evrything has a relay startup and imeditate
 > >stop button
 > >Diode protection capacitor 16 kV 1600 pF
 > >
 > >Main primary capacitors
 > >
 > >200 pF 20 kV
 > >400 pF 16 kV
 > >
 > >in parallel for 600 pF
 >
 >
 > that is a little small, but will work.  A larger cap will help
 > to pull more power through the coil by lowering the tank impedance.
 >
 >
 > >Topload copper pipe oldered arround copper circle and a insulator on top
(
 > >very small toroid)
 >
 >
 > very good.
 >
 >
 > >It has a anode current meter too, at biggest sparks anode current was
almost
 > >300 mA.
 >
 >
 > Was the tube plate red at this power level?
 >
 >
 > >This is what im seeking now
 >
 >
 > What is the grid resistance and grid capacitance?
 >
 >
 > >Im going to rebuild the coil on a new wodden platform, i guess my primary
 > >and feedback were BS.
 > >
 > >By reading the Steves site im plaining to use 0.4 mm wire for feedback
and 2
 > >mm wire for primary? What do you think?
 >
 >
 > Yes, that is good.
 >
 >
 > >Well write as much you can and as much you want :-).
 >
 >
 > How long are the sparks again, I forget?  Did you try tapping
 > along the primary to tune the coil?  Or did you tune some other way?
 >
 > In general as long as you more or less copy someone's design,
 > you should tend to get similar results.  To get longest sparks
 > will take optimization for staccato.  In other words if the coil
 > is made to work wtih the tube not too red without staccato,
 > then it will not give much more spark length with staccato.
 > But if teh coil is optimized for staccato, then the tube will
 > get too red without staccato, but the spark will be longer.
 >
 > John
 >
 >
 > >Best regards
 > >
 > >Kreso Bukvic
 >
 >
 >
 >
 >
 >