I reduced my grid feedback resistance to 2500 ohms. That added about 1". I added one more capacitor to the voltage doubler for a total of 3 uF. That added about 1". So I am currently at 20" with staccato (interrupter) which is not bad. Tuning is as good as it can get. The 833A is a NOS Amperex (1971 vintage) so I am sure it is good and strong. I don't see any sign of gas (blue glow) within the tube. The amp meter shows about 15 amps at 140 volts for 2100 watts during each interrupter pulse. I have tried different length discharge terminals. The one that I started with is as good as any. So I don't know where to go from here to get any more spark length.
I have also added a pre-heat feature for the filament to prolong its life. I used a switchable 150 ohm resistor on the 120 volt side. I recently acquired a commercial 10 volt, 12 amp filament transformer. I am considering replacing my custom MOT-based filament transformer with it because it is so much more efficient. My MOT-based filament transformer draws about 6 amps at 120 volts so that is about 700 watts! The commercial transformer draws about 1 amp at 120 volts and stays completely cool.
If you have any suggestions, I would appreciate hearing them.
----- Original Message -----
From: "Chris Reeland" <chrisreeland@xxxxxxxxx>
To: "Futuret" <futuret@xxxxxxx>, "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, March 14, 2018 6:32:39 PM
Subject: Re: [TCML] VTTC MOT question
Hi Steve,
Been quiet on your tube coil currently...
Did you try any changes recently?
I hope you keep at it.
Me, I recently got my secondary rewound and got my coil put back together.
Fired it up a couple of days ago. No great initial gains, but after pulling
an all nighter (never went to bed, went straight to work, did not want to
stop) of testing, tuning, and experimenting, I made very great gains. I am
at 29" now. I feel there is just a bit more also, with a change and fine
tuning. First break out on the variac is now at 60-65%. I will give some
more thorough description of what I all did probably this weekend sometime.
I will have some more time on Thursday and Friday to make a change and try
futher tuning to get just a bit more.
Here is a picture I took.
Yardstick hanging behind.
https://photos.app.goo.gl/P4Z8CpNPkjBKWaww2
Chris
Sent from my LG V20
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