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RE: [TCML] Negative bias in a VTTC
Hi Vladi, I urge you to view my VTTC on youtube (big VTTC). I posted some
video of it running, along with o'scope pictures and Spectrum Analyzer
pictures. You have got to hit the tube's grid hard enough to completely turn
it off. On a low mu power triode, this generally takes several thousand
volts negative. Low mu tubes are generally better for Tesla coils. You also
need to have enough primary turns to properly load the tube. Too few turns
causes the tube to run hot. Around 25-30 turns of primary is a good start.
Then match the primary capacitor. The tickler winding needs to be a few
turns less. The grid leak resistor controls the current through the tube.
Monitor the cathode current and set accordingly. James
-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Vladimiro Mazzilli
Sent: Wednesday, September 22, 2010 10:44 AM
To: tesla@xxxxxxxxxx
Subject: [TCML] Negative bias in a VTTC
Hi all.
A friend of mine have problem with grid leak network of a single 833 VTTC.
He started with a 5k resistor and have increased its value reaching over
25k, but with a MOT without doubler, he has always the plate very red.
I noted that triodes have different plate current value with 0V biased grid
independently from the power of the tube: 811A is very simple to bias at 0V
because the plate at 2000V reach only 20mA of plate current from the curves,
otherwise 833 drain 500mA from plate, with grid biased at 0V and with 2000V
on plate.
Had anyone made test with grid leak resistor connected at a variable dc or
'in phase' ac and grid leak capacitor grounded?
Cheers
Vladi
________________________________
Vladimiro Mazzilli
Ricerca & Sviluppo
Aros
Via Somalia 20
20032 Cormano (MI)
Tel. +39 02 66327266 - Fax. +39 02 66327528
Skype Id: - VoIp:
E-mail: V.Mazzilli@xxxxxxx
Web: www.aros.it<http://www.aros.it>
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