Re: [TCML] 833A VTTC Novice

[Futuret <futuret@xxxxxxx>]

 William,

I'm not sure if you measured the output voltage with the tube connected to the
filament transformer,
but it should be done that way to get the true voltage as loaded by
the filament.  Use the actual hook-up wire (type and length) that you'll
be using in the final project.  Also the voltage should be measured at the tube pins
while the filament is lit.  This way you get a true voltage reading... the true
voltage the tube will actually receive.

It doesn't matter if there's some voltage drop in the wires as long at
you obtain the desired voltage at the tube pins.  If you need more
voltage you can add more turns to your modified MOT secondary 
winding.  

I don't worry about burn-in, I just heat the filaments for a minute or so
before firing up the coil.  There are methods to scavenge extra gas
in the tube by embedding it into the tube walls using an external
source HV source.  Again I don't bother.  

I never worry about an unbalanced filament because tubes can run
for 10,000 hours or so, so even if an unbalanced filament cuts the
tube life to 5000 hours, that's probably more time then you'll ever
run the VTTC.   

Cheers,
John

 

 

-----Original Message-----
From: Wm A Tickhill <wtickhill@xxxxxxxxx>
To: tesla <tesla@xxxxxxxxxx>
Sent: Fri, Nov 18, 2011 7:44 pm
Subject: [TCML] 833A VTTC Novice


Thanks to everyone for responding to my inquiry re (2)833A Vttc Specs.

I am gathering parts for an initial hash up, and I have a few

questions. Two 833As require 20 amps @ 10 volts.

 I have rewound a MOT to serve as the filiment transformer, the output

is 10.55 volts @123 volts in ( I have Variacs ). I tested using the

series resistance of x00 feet of

#14 awg wire, @19 amp current draw the voltage drop is .2 volt.



1  Is this voltage drop excessive, should I remove the shunts?



2  How long should the tubes burn in, and do I simply power up the

filiment supply and let them cook?



3  Should I scrap the MOT ( unbalanced ) as filiment transformer idea?



Thanks    William A Tickhill

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