Re: [TCML] Re: having problems with vttc tuning...

[FutureT@xxxxxxx]

In a message dated 3/16/2008 3:54:07 P.M. US Eastern Standard Time,  
giorgiodidon@xxxxxxxxx writes:

hi all,  thank you for your answers.
i tried  to do everything you suggested  but nothing.
i tested the tube, no short between filament and grid
and  between grid and anode. so i assume the tube is ok (!?).
what about grid  leak resistor, maybe 1400ohms is too weak?
do you thing that trying with  bigger one will work?
in  this
http://www.stevehv.4hv.org/VTTC2.htm
vttc steve uses a 10kohm grid  leak resistor...

i doubled the mot also.

thank  you
giorgio



Giorgio,
 
The 1400 ohm resistor should at least work even if it doesn't work
perfectly.  If you disconnect the grid connection to the tube,  and
then run the coil, the tube plate should get red probably....
depending on the type of tube.  Is this an 833A tube you're  using?
If the tube plate doesn't get red, it may have low emission, or be
dead or something.  I'm assuming the filament lights up  correctly,
and that you verified correct filament voltage on the filament?  
Does the coil draw current?  Maybe you have a bad capacitor
or something shorted, or incorrect wiring.  I assume you copied
an existing coil, or used JavaTC to figure out the primary tune  point,
or proper tank cap value for proper tuning.  But since the  fluorescent
tube held near the primary doesn't light, this means it's not even
oscillating at all, so there's something very wrong, I don't know  what.
I guess you're using the level-shifting power supply concept with
the HV diode and capacitor?  There's no staccato  feature installed, right?
Maybe the HV diode is facing the wrong way? (wrong polarity?).   If
you built the staccato feature, you should first get the coil running  without
the staccato.  Just jumper across the triac or scr with a wire, or  remove
the triac or scr and put a wire in it's place.  You're not using  a
304TL tube are you?
 
John  



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