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

R: [TCML] First light, small VTTC



So seems better to use thin wire to have a good grid driving, but not too tall in order to no decrease the spark length?

Vladi



Vladimiro Mazzilli
Ricerca & Sviluppo
Aros Srl
Via Somalia 20
20032 Cormano (MI)
Tel. +39 02 66327266 - Fax. +39 02 66327528
email: V.Mazzilli@xxxxxxx
Web: http://http://www.aros.it
 -----------------------------------------------------------------------------------------------------
Chi riceve il presente messaggio e` tenuto a verificare se lo stesso non gli sia pervenuto per errore. In tal caso e` pregato di avvisare immediatamente il mittente e, tenuto conto delle responsabilita` connesse all'indebito utilizzo e/o divulgazione del messaggio e/o delle informazioni in esso contenute, voglia cancellare l'originale e distruggere le varie copie o stampe.

The receiver of this message is required to check if he/she has received it erroneously. If so, the receiver is requested to immediately inform the sender and - in consideration of the responsibilities arising from undue use and/or disclosure of the message and/or the information contained therein - destroy the original message and any copy or printout thereof.

-----Messaggio originale-----

Da: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] Per conto di futuret@xxxxxxx
Inviato: martedì 28 ottobre 2008 0.34
A: tesla@xxxxxxxxxx
Oggetto: [TCML] First light, small VTTC


I powered up my new small 4-125A VTTC and got 4" sparks
so far.  They are the fuzzy type sparks.  More tuning is needed.
I tried removing the MOT shunts, but the sparks didn't get
much longer so far.  The tube plate gets red which is not surprising
for a 4-125A tube.  I tied the grids together on the tube, and
I'm using 1500 ohms for the grid leak R.  I tried 2500 ohms but
that gave very weak sparks.  On a previous coil which used
a 4-250A tube, I got the same spark output with grids
tied together as when feeding the screen grid from a
dropping resistor.  That coil also used a 1500 ohm grid leak resistor.
There is no toroid on the coil.  Some tests I did in the past
showed that even the choice of vacuum tube type can
make the sparks either fuzzy or sword-like.  This may suggest
that some parameter was not optimized for each tube.

I did a quick experiment with a raised grid coil.  Normally
I allow about 1/2" space between the primary and grid coil.
I raised the grid coil by about 3" as a test.  The sparks
got much weaker.  So I moved the grid coil tap so I used
20 turns instead of 12.  This increased the spark length
almost to what it was with the lowered grid coil.  This
secondary is only 8.875" long, so raising the grid coil
by 3" is a lot for this small coil.  I tried various grid
coil heights and generally speaking, the spark output
varied with the grid coil height.  A higher grid coil
gave weaker output sparks.  These results are
preliminary because the coil still needs more tuning.

Cheers,
John



_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla



_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla