Re: All who know VTTC stuff ;-).

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

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

Nope it does not produce swordish sparks! I rewinded the secondary today. It
makes now ~20 cm sparks.

Is there a chance for more?

Best Regards

Kreso Bukvic
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, July 15, 2004 3:45 AM
Subject: Re: All who know VTTC stuff ;-).


 > Original poster: FutureT-at-aol-dot-com
 >
 > In a message dated 7/14/04 7:39:40 PM Eastern Daylight Time,
 > tesla-at-pupman-dot-com writes:
 >
 > >Original poster: Kreso Bukvic <kreso.bukvic-at-kc.htnet.hr>
 > >
 > >Hy i would have 7 questions.
 > >
 > >1. How to determine is the VTTC in perfect tune or is it not?
 >
 >
 > Kreso,
 >
 > You can build a variable capacitor or change the capacitance
 > by adding or subtracting small capacitors to change the capacitance
 > in small steps to see if the spark length improves at any point.
 >
 > You can also change the primary tap point.  However you
 > must be aware that this changes the tank impedance and
 > may cause changes unrelated to tuning.  Small tap changes
 > will reflect tuning changes more than impedance changes
 > especially if the tuning is close to begin with.
 >
 > Another way to check tuning is to vary the size of the toroid.
 > If the sparks get longer with a smaller or larger toroid, then
 > the tuning was probably not quite right originally.
 >
 > Interestingly, the tuning if it is close will not affect the spark
 > length, however the tube will run redder for that spark length.
 > In other words better tuning may not lengthen the spark, but
 > will make the tube run cooler and reduce the power draw.
 > I'm assuming you want to tune for longest sparks with minimal
 > input power.
 >
 > Adjustments of grid feedback, grid resistance, tuning, coupling,
 > etc, tend to interact.  Much adjustment may be needed before
 > optimal results are achieved.  My best VTTC's achieve an
 > "efficiency" of:   (without staccato)
 >
 >    spark length inches = 0.5*sqrt input watts.
 >
 > >2. If the secondary is wound slopili and has many knick does this
influence
 > >the spark length?
 >
 >
 > Probably not much influence.
 >
 > >3. If i will rewind the secondary with same number of turns but without
 > >knicks and overlaps, will i have ot retune it?
 >
 >
 > Probably the tuning will be very similar.
 >
 > >4. I just noticed the tube has a small airbuble in glass ( i could post a
 > >picture). It works perfectly, but should i be worried?
 >
 >
 > Probably this is not a problem.
 >
 > >5. If the filament transformer is rated fro much higher current than the
 > >tube needs can it do any harm ( my tube needs 5 V 14.1 A i have 5 V 30
A).
 >
 >
 > Current rating doesn't matter as long as it's enough.  What matters is
 > the voltage.  The tube will only draw the rated current if
 > the voltage is correct.
 >
 > >6. Will stacatto improve sparklength? On my SSTC it improwes it by ~200
%.
 >
 >
 > It depends.  Sometimes it won't help, other times it will.  By using
 > staccato, you can increase the peak power but keep the average
 > power low for longer sparks.
 >
 > >7. Will an improper diode decrease performance? I curently have 6 diode
 > >bridges in series ( greatzes).
 >
 >
 > I guess this if for a voltage doubler or level shifter?  Probably not
 > a lot of effect on performance will be seen.  Operation on filtered
 > DC without staccato will cause the sparks to be short, but draw
 > terrific power.  Raw AC operation with staccato tends to be
 > efficient.  Staccato can be used with filtered DC but is tricky
 > to implement.  Staccato is easily implemented using a mechanical
 > rotary switch from the filament to ground.  If the tube is a tetrode,
 > an AC 50Hz sample of the power line can be fed to the screen
 > grid to simulate AC operation and make electrical staccato operation
 > easier.
 >
 > Do you ever get the very straight swordlike sparks such as can
 > be seen at my website?  (in the staccato mode)
 >
 >
<http://hometown.aol-dot-com/futuret/page3.html>http://hometown.aol-dot-com/futuret/
page3.html,
 >
 >
 > click on tube coils (I think).
 >
 > John
 >
 >
 > >Thanks for answers
 > >
 > >Best Regards
 > >
 > >Kreso Bukvi
 > >
 >
 >
 >
 >
 >
 >